BoilerFaultCodes.com

Vaillant Home Combi Fault Codes

Combi Natural Gas 25-35 kW 2015-present
GC Numbers: 47-044-6447-044-65

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Most common fault codes

F.00
Your boiler has stopped working because it cannot communicate with the internal sensor that monitors the temperature of the water leaving the unit.
Gas Safe engineer required · £90-160
F.01
Your boiler has stopped working because it cannot communicate with the sensor that monitors water returning from your radiators.
Gas Safe engineer required · £100-180
F.10
Your boiler has stopped working because it thinks the internal pipe temperature sensor has a faulty electrical connection.
Gas Safe engineer required · £90-180

All 40 fault codes

Code Severity Plain English
F.00 High Your boiler has stopped working because it cannot communicate with the internal sensor that monitors the temperature of the water leaving the unit.
F.01 High Your boiler has stopped working because it cannot communicate with the sensor that monitors water returning from your radiators.
F.10 High Your boiler has stopped working because it thinks the internal pipe temperature sensor has a faulty electrical connection.
F.11 High Your boiler has detected an electrical issue with the pipe sensor that monitors water returning to the unit, causing it to shut down for safety.
F.13 Medium Your boiler's hot water sensor has developed an electrical fault, meaning the system cannot tell how hot your water is and has likely stopped heating it for safety.
F.20 High Your boiler has shut itself down because it has become too hot inside, likely due to a circulation issue or a lack of water.
F.22 High Your boiler has switched itself off because the water pressure in the system has dropped too low.
F.23 High Your boiler has shut down because the water leaving the unit is getting much hotter than the water returning, suggesting a circulation problem through your radiators.
F.24 High Your boiler has shut down because it is heating up much faster than it should, usually because the water isn't moving through the system properly.
F.25 High Your boiler has shut down because the exhaust gases are getting too hot, which is a safety measure to prevent damage to the internal components.
F.27 High Your boiler has sensed a flame when there shouldn't be one, so it has shut down as a safety precaution.
F.28 High Your boiler has tried to light itself three times but failed, meaning you currently have no heating or hot water because the gas flame isn't staying on.
F.29 High Your boiler was working but the flame has unexpectedly gone out, causing the system to stop for safety.
F.32 High Your boiler's fan is not spinning at the correct speed, which prevents the unit from venting fumes safely and stops it from firing up.
F.49 High Your boiler's internal communication system has lost power, meaning the main control board cannot talk to the external controls or thermostats.
F.61 High Your boiler has detected an internal communication problem between its main computer and the gas valve, preventing it from lighting safely.
F.62 High Your boiler is struggling to turn off the gas supply when it should, causing the system to shut down for safety.
F.63 High Your boiler's internal computer brain is having trouble reading its memory, which prevents the system from starting up safely.
F.64 High Your boiler has detected an internal electrical conflict or a sensor failure that is preventing it from running safely.
F.65 High Your boiler's internal control board has become too hot and has shut itself down to prevent damage.
F.67 High Your boiler's control system is receiving an incorrect electrical signal from the sensor that monitors whether the flame is lit, causing it to shut down for safety.
F.68 High Your boiler is struggling to keep the flame lit steadily, which is causing it to shut down for safety.
F.70 High Your boiler's computer brains have lost their identity settings, usually because a new part was installed without being correctly programmed.
F.71 High Your boiler's temperature sensor is stuck on a single reading, meaning the system cannot accurately monitor how hot the water is getting.
F.72 High Your boiler has sensed that its two main temperature sensors aren't agreeing with each other, so it has shut down to prevent potential overheating.
F.73 High Your boiler is unable to accurately measure its internal water pressure, causing it to shut down for safety.
F.74 High Your boiler is struggling to read its internal water pressure correctly because the sensor is sending an unusual signal.
F.75 High Your boiler has stopped working because it cannot detect the necessary water movement to start the heating process safely.
F.76 High Your boiler has shut down because a safety sensor has detected that the main component which heats your water has reached a dangerously high temperature.
F.77 High Your boiler has detected an issue with the drainage pump or the flap that prevents fumes from blowing back into the unit, causing it to shut down for safety.
F.78 Medium Your boiler is having trouble communicating with an external control sensor, which means it cannot accurately measure the temperature of the hot water leaving the unit.
F.83 High Your boiler is firing but doesn't detect the water warming up as expected, so it has shut down to prevent overheating.
F.84 High Your boiler is confused because the sensors that monitor the water going in and out are giving conflicting readings.
F.85 High Your boiler has detected that a temperature sensor is not fitted correctly to its pipe, preventing it from reading the water temperature safely.
F.86 Medium Your boiler has detected an issue with the safety switch protecting your underfloor heating system, causing it to stop running to prevent heat damage.
F.87 High Your boiler is unable to start the flame because the internal spark plug that ignites the gas is disconnected or faulty.
F.88 High Your boiler has detected a problem with how it controls the gas supply, meaning it cannot safely light the flame to provide heating or hot water.
F.89 High Your boiler has detected that the internal pump is not moving water around the system correctly, preventing it from heating your home.
F22 High Your boiler has stopped working because the water pressure is too low for it to operate safely.
P.07 Low Your boiler is currently running a self-cleaning mode to remove trapped air bubbles from the pipes and pump.

Status & diagnostic codes

These codes indicate your boiler's operating state or a diagnostic reading — not necessarily a fault. Status codes (S.) mean normal operation; diagnostic codes (D.) are informational readings used by engineers.

Code Type Description
S.04 Status Your boiler is working perfectly and is currently running specifically to provide heat for your radiators.
S.14 Status Your boiler is working exactly as it should and is currently heating up the water for your taps.

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