Identify your appliance
Models and ranges Vaillant Selected references from manufacturer documentation, including older generations. Check the full name and suffix on the rating plate: manuals and error codes can differ by version and country.
Boiler display
Vaillant error codes Check the model, note the full code and learn the useful precautions before the diagnosis.
Before reading the list Selection for Vaillant condensing boilers of the ecoTEC family. The meaning can vary by model: always check the exact manual.
36 error codes found
S.00 Heating: no heat demand This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault. View details S.02 Heating pump pre-run This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault. View details S.03 Burner ignition in progress This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault. View details S.04 Burner running This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault. View details S.07 Pump overrun This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault. View details S.08 Burner anti-cycling time This display describes the appliance’s normal operating state (standby, pump pre-run, ignition, burner running…). It is not a fault. View details F.00 Flow temperature sensor interrupted A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details F.01 Return temperature sensor interrupted A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details F.10 Flow temperature sensor short circuit A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details F.11 Return temperature sensor short circuit A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details F.13 Hot-water cylinder sensor short circuit A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details F.20 Safety temperature limiter tripped 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. View details F.22 Low-water protection 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. View details F.23 Flow/return temperature difference too large Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit. View details F.24 Abnormally fast temperature rise Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit. View details F.25 Flue gas temperature too high 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. View details F.27 False flame signal 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. View details F.28 Burner fails to start The burner failed to light or the flame was not detected: interrupted gas supply, worn ignition or sensing electrode, gas valve or condensate drain. View details F.29 Re-ignition impossible after flame loss The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode. View details F.32 Fan fault The fan is not running at the expected speed or does not stop: a dirty or worn fan, wiring or the electronic control. View details F.49 Undervoltage on the eBUS link A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.61 Gas valve control fault A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.62 Gas valve delayed shut-off A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.63 Electronic memory (EEPROM) fault A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.64 Circuit board or sensor (electronics) fault A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.65 Circuit board temperature too high A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.68 Unstable flame signal The flame went out during operation: disturbed air supply or flue, unstable gas pressure or a dirty sensing electrode. View details F.70 Invalid appliance code A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.72 Abnormal deviation between flow and return sensors A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details F.73 Water pressure sensor not connected A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.74 Water pressure sensor fault A control, communication or electronic memory fault has been detected: circuit board, controller, wiring or power supply. View details F.75 No pressure change detected when the pump starts Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit. View details F.77 Flue flap or condensate pump fault Condensate or flue gas removal is disturbed: a blocked or frozen condensate pipe, condensate pump, flap or flue duct obstructed. View details F.83 No temperature change at start (lack of water) Water circulation is insufficient or detected as abnormal: air in the circuit, a blocked or weak pump, closed valves or a dirty circuit. View details F.84 Inconsistent flow/return temperatures A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details F.85 Sensors fitted on the same pipe A temperature sensor is sending an impossible value: a faulty sensor, or a loose or short-circuited cable or connector. View details See the Vaillant codes
