Understand the display,
without guessing the fault.

250 error codes found

• S.00Heating: no heat demandVaillant · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.02Heating pump pre-runVaillant · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.03Burner ignition in progressVaillant · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.04Burner runningVaillant · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.07Pump overrunVaillant · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.08Burner anti-cycling timeVaillant · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• F.00Flow temperature sensor interruptedVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.01Return temperature sensor interruptedVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.10Flow temperature sensor short circuitVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.11Return temperature sensor short circuitVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.13Hot-water cylinder sensor short circuitVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.20Safety temperature limiter trippedVaillant · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F.22Low-water protectionVaillant · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• F.23Flow/return temperature difference too largeVaillant · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F.24Abnormally fast temperature riseVaillant · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F.25Flue gas temperature too highVaillant · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F.27False flame signalVaillant · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• F.28Burner fails to startVaillant · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• F.29Re-ignition impossible after flame lossVaillant · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• F.32Fan faultVaillant · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• F.49Undervoltage on the eBUS linkVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.61Gas valve control faultVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.62Gas valve delayed shut-offVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.63Electronic memory (EEPROM) faultVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.64Circuit board or sensor (electronics) faultVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.65Circuit board temperature too highVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.68Unstable flame signalVaillant · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• F.70Invalid appliance codeVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.72Abnormal deviation between flow and return sensorsVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.73Water pressure sensor not connectedVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.74Water pressure sensor faultVaillant · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.75No pressure change detected when the pump startsVaillant · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F.77Flue flap or condensate pump faultVaillant · Condensate or flue gas removal is disturbed: a blocked or frozen condensate pipe, condensate pump, flap or flue duct obstructed.CautionView details
• F.83No temperature change at start (lack of water)Vaillant · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F.84Inconsistent flow/return temperaturesVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.85Sensors fitted on the same pipeVaillant · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• S.00Heating: no heat demandBulex · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.02Heating pump pre-runBulex · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.03Burner ignition in progressBulex · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.04Burner runningBulex · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.07Pump overrunBulex · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.08Burner anti-cycling timeBulex · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• S.37Fan malfunctionBulex · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• S.41Water pressure too highBulex · The circuit pressure is too high: overfilling, a worn expansion vessel or strong heating of the circuit.CautionView details
• S.42Heat demand blocked by an internal malfunctionBulex · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• S.53Safety function triggered by lack of waterBulex · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• S.54Appliance on standby due to lack of waterBulex · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• F.00Flow temperature sensor faulty or badly connectedBulex · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.01Return temperature sensor faultyBulex · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.10Flow temperature sensor short circuitBulex · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.11Return temperature sensor short circuitBulex · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F.20Safety temperature limiter trippedBulex · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F.22Low-water protectionBulex · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• F.23Flow/return temperature difference too largeBulex · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F.24Abnormally fast temperature riseBulex · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F.25Flue gas temperature too highBulex · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F.27False flame signalBulex · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• F.28Burner fails to startBulex · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• F.29Re-ignition impossible after flame lossBulex · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• F.32Fan faultBulex · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• F.49Undervoltage on the eBUS linkBulex · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.61Gas valve control faultBulex · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.63Electronic memory (EEPROM) faultBulex · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F.75No pressure change detected when the pump startsBulex · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 0AInsufficient gas pressureViessmann · The gas pressure or flow to the appliance is insufficient: a closed valve, the meter or network, or a gas safety component.CautionView details
• 0FServicing requiredViessmann · The appliance is signalling that servicing is due (interval reached, descaling or periodic check). This is usually not a fault.NormalView details
• A2Insufficient pressure in the systemViessmann · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• A4Pressure too high in the systemViessmann · The circuit pressure is too high: overfilling, a worn expansion vessel or strong heating of the circuit.CautionView details
• A8Air detected in the circulation pumpViessmann · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• A9Circulation pump blockedViessmann · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E3Fault in the safety chainViessmann · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F0Internal electronics errorViessmann · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F1Flue gas overheatingViessmann · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F2Safety temperature limiter trippedViessmann · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F3Flame signal at burner startViessmann · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• F4No flame signalViessmann · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• F8Gas valve closes too lateViessmann · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• F9Fan too slow at burner startViessmann · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• FAFan not stopped when the burner is offViessmann · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• CEInsufficient circuit pressureBosch · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• EAFlame not detectedBosch · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• 6ANo flame after ignitionBosch · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• A1Pump without water or insufficient circulationBosch · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• A7Hot-water temperature measurement faultBosch · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A8Communication link interruptedBosch · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• C6Fan running too slowlyBosch · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• E2Flow temperature sensor faultBosch · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E9Temperature safety activatedBosch · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F7Flame signal while the appliance is offBosch · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• FAFlame signal after the gas has closedBosch · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• CEInsufficient circuit pressureJunkers · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• EAFlame not detectedJunkers · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• 6ANo flame after ignitionJunkers · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• A1Pump without water or insufficient circulationJunkers · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• A7Hot-water temperature measurement faultJunkers · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A8Communication link interruptedJunkers · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• C6Fan running too slowlyJunkers · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• E2Flow temperature sensor faultJunkers · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E9Temperature safety activatedJunkers · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F7Flame signal while the appliance is offJunkers · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• FAFlame signal after the gas has closedJunkers · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• CEInsufficient circuit pressureBuderus · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• EAFlame not detectedBuderus · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• 6ANo flame after ignitionBuderus · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• A1Pump without water or insufficient circulationBuderus · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• A7Hot-water temperature measurement faultBuderus · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A8Communication link interruptedBuderus · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• C6Fan running too slowlyBuderus · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• E2Flow temperature sensor faultBuderus · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E9Temperature safety activatedBuderus · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F7Flame signal while the appliance is offBuderus · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• FAFlame signal after the gas has closedBuderus · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• B14Water pressure too lowDe Dietrich · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• B22The flame goes out during operationDe Dietrich · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• E04Repeated flame detection failureDe Dietrich · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• E07Water pressure too lowDe Dietrich · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• E08Fan faultDe Dietrich · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• E10Water circulation faultDe Dietrich · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E32Descaling signalledDe Dietrich · The appliance is signalling that servicing is due (interval reached, descaling or periodic check). This is usually not a fault.NormalView details
• L14Unsuccessful ignition attemptsDe Dietrich · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• M04Servicing requiredDe Dietrich · The appliance is signalling that servicing is due (interval reached, descaling or periodic check). This is usually not a fault.NormalView details
• 101Appliance overheatingAriston · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• 103Insufficient water circulationAriston · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 104Insufficient circulation in the primary circuitAriston · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 108Insufficient water pressureAriston · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• 501No flame detectedAriston · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• 10Outdoor sensor faultATAG · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• 20Flow sensor faultATAG · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• 40Return sensor faultATAG · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• 50DHW sensor fault (iC)ATAG · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• 61Bus communication faultATAG · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 78Water pressure reading out of rangeATAG · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 105Venting programme active after power-onATAG · This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault.NormalView details
• 110Safety temperature exceededATAG · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• 111Maximum pressure exceededATAG · The circuit pressure is too high: overfilling, a worn expansion vessel or strong heating of the circuit.CautionView details
• 117Excessive pressure or pump pressure riseATAG · The circuit pressure is too high: overfilling, a worn expansion vessel or strong heating of the circuit.CautionView details
• 118Insufficient pressure or pump pressure riseATAG · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• 129Fan fails to startATAG · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• 133No flame after five attemptsATAG · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• 151Fan speed control or control unit faultATAG · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 154Flow temperature rises too rapidlyATAG · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E01Five unsuccessful ignition attemptsACV · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• E02Flame detected before ignitionACV · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• E03Boiler temperature above 105 °CACV · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• E05Incorrect fan speed or feedbackACV · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• E12Incorrect EEPROM configurationACV · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E13Reset limit reachedACV · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E82Excessive temperature difference: blockingACV · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E83Excessive temperature difference: lockoutACV · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E86Pump failureACV · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E91System sensor short circuitACV · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E92System sensor open circuitACV · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E99Display/control communication lostACV · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 101Overtemperature shutdownChaffoteaux · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• 103Water circulation faultChaffoteaux · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 104Water circulation faultChaffoteaux · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 105Water circulation faultChaffoteaux · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 106Water circulation faultChaffoteaux · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 107Water circulation faultChaffoteaux · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• 108Insufficient heating circuit pressureChaffoteaux · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• 305Electronic control board faultChaffoteaux · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 306Electronic control board faultChaffoteaux · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 307Electronic control board faultChaffoteaux · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 501Flame absentChaffoteaux · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• 601Flue safety tripped (CF)Chaffoteaux · Condensate or flue gas removal is disturbed: a blocked or frozen condensate pipe, condensate pump, flap or flue duct obstructed.CautionView details
• 602VMC safety tripped (VMC)Chaffoteaux · Condensate or flue gas removal is disturbed: a blocked or frozen condensate pipe, condensate pump, flap or flue duct obstructed.CautionView details
• A01Burner ignition or detection failedRiello · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• A10Burner ignition or detection failedRiello · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• A02Limit thermostat trippedRiello · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• A20Limit thermostat trippedRiello · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• A03Air/flue safety or fan faultRiello · Condensate or flue gas removal is disturbed: a blocked or frozen condensate pipe, condensate pump, flap or flue duct obstructed.CautionView details
• A30Air/flue safety or fan faultRiello · Condensate or flue gas removal is disturbed: a blocked or frozen condensate pipe, condensate pump, flap or flue duct obstructed.CautionView details
• A04Primary circuit pressure too lowRiello · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• A40Primary circuit pressure too lowRiello · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• A06DHW NTC sensor faultRiello · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A60DHW NTC sensor faultRiello · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A07Heating/flow sensor or temperature differential faultRiello · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A70Heating/flow sensor or temperature differential faultRiello · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A08Return sensor or temperature differential faultRiello · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• A99Too many resets from the remote controlRiello · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E10Outdoor sensor faultChappée · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E20Boiler flow sensor faultChappée · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E28Flue safety sensor faultChappée · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E40Return sensor faultChappée · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E50DHW sensor faultChappée · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E110Boiler circuit overheatingChappée · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• E111Boiler circuit overheatingChappée · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• E117Water overpressureChappée · The circuit pressure is too high: overfilling, a worn expansion vessel or strong heating of the circuit.CautionView details
• E118Water pressure too lowChappée · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• E125Pump monitoring faultChappée · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E128Flame lost during operationChappée · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• E130Excessive flue temperatureChappée · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• E133No flame during the safety periodChappée · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• E151Internal control faultChappée · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E160Fan faultChappée · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• E385Supply voltage too lowChappée · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E386Incorrect fan speedChappée · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• E430Water flow monitoring faultChappée · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E:00Flow or return sensor faultOertli · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E:01Flow temperature above operating limitOertli · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• E:02Return temperature higher than flowOertli · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E:03Control panel faultOertli · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E:04No flame after five startsOertli · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• E:05Ionisation faultOertli · The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode.CautionView details
• E:06Unwanted flame detectedOertli · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• E.04.01Flow sensor shorted or reading above rangeRemeha · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E.04.03Temperature above safety limitRemeha · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• E.04.07Deviation between the two flow sensorsRemeha · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E.04.10Five burner starts failedRemeha · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• E.04.12Flame detected before startingRemeha · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• E01Flame detection circuit faultSime · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• E02Safety thermostat trippedSime · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• E04Insufficient system pressureSime · The water pressure in the heating circuit is too low, often because of a small leak, recent radiator bleeding or a slow loss over the months.CautionView details
• E05Air pressure switch trippedSime · Condensate or flue gas removal is disturbed: a blocked or frozen condensate pipe, condensate pump, flap or flue duct obstructed.CautionView details
• E06Hot-water sensor faultSime · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E07Flow sensor faultSime · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• E09No water circulationSime · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• E11Unwanted flame signalSime · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• E12Gas valve modulator disconnectedSime · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E28Maximum consecutive resets reachedSime · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E37Insufficient mains voltageSime · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• E40Incorrect mains frequencySime · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 01Combustion chamber thermostat trippedWolf · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• 02Temperature limiter trippedWolf · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• 03eSTB sensor difference above 6 °CWolf · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• 04No flame during startupWolf · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• 07Flue temperature above 110 °CWolf · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• 24Fan speed too lowWolf · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• 26Fan does not stopWolf · The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control.CautionView details
• 27DHW or stratified cylinder sensor faultWolf · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• 30Invalid combustion controller EEPROM dataWolf · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• 3223 V AC supply outside rangeWolf · A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply.CautionView details
• F11eSTL temperature above 105 °CWeishaupt · A temperature safety has tripped: the water is not circulating enough (air, pump, closed valves, dirty filter or heat exchanger) or the circuit is short of water.CautionView details
• F15Excessive flow/return differenceWeishaupt · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F18Excessive eSTL/flow differenceWeishaupt · Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit.CautionView details
• F21No flame formation at burner startWeishaupt · The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain.CautionView details
• F23Simulated flame detectedWeishaupt · The appliance detects a flame when the burner should be off, or after the gas has closed. The gas valve or the sensing circuit may be faulty.DangerView details
• F30eSTL sensor defectiveWeishaupt · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• F31Flue sensor defectiveWeishaupt · A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector.CautionView details
• ErrInternal or external sensor fault — position 6Radson · On this Digital RF thermostat, Err in position 6 indicates an internal or external (floor) sensor fault. The flashing symbol identifies the sensor; regulation stops. This message does not diagnose the boiler.CautionView details
• LoLower floor limit active — position 4Radson · Lo in position 4 indicates the lower limitation associated with the floor sensor. It is not a boiler pressure code or proof of a sensor fault.NormalView details
• HiUpper floor limit active — position 4Radson · Hi in position 4 indicates the upper limitation associated with the floor sensor, according to the FR and NL manual sections. It is not a burner overheat code.NormalView details
• SnrSensor fault — Hydrostat 3250-PlusSaint Roch · Snr identifies a sensor or connection problem. The segmented S can resemble a 5.CautionView details
• 8Microprocessor fault — Hydrostat 3250-PlusSaint Roch · The troubleshooting section identifies display 8 as a microprocessor failure requiring professional control replacement.CautionView details
• 888Microprocessor fault — Hydrostat 3250-PlusSaint Roch · 888 identifies the same microprocessor fault as 8 in the troubleshooting table.CautionView details
• LOW WATERRed indicator on or blinking — low water / lockoutSaint Roch · With Electro-Well, a steady light means water is not detected; blinking means lockout when manual-reset mode is configured. Poor continuity in a standard immersion well can cause a false indication.DangerView details
• LEDs + displayIndicators and temperature blinking alternately — overheatingSaint Roch · This visual signal indicates a detected temperature of 250 °F (about 121 °C) and burner lockout. It is not an alphanumeric code.DangerView details
• PurNormal status: thermal pre-purgeSaint Roch · The control uses residual heat before allowing the burner to fire. Pur is an operating status.NormalView details
• HI TEMPIndicator: high limit reachedSaint Roch · The set high limit has been reached; the burner remains off until the specified temperature drop. This indicator can occur in normal operation.NormalView details
• TARGETECONOMY indicator: target temperature reachedSaint Roch · The economy target temperature has been reached. The control pauses the burner; this indicator regularly appears during normal operation.NormalView details