BoilerFaultCodes.com

Vaillant Thermocompact Fault Codes

System Natural GasLPG 12-35 kW 1995-2005 Discontinued
GC Numbers: 41-044-0141-044-0241-044-0341-044-0441-044-05

Replaced by: ecoTEC plus

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Most common fault codes

F.00
Your boiler has stopped working because it can no longer accurately measure the temperature of the water leaving the unit due to a sensor or wiring fault.
Gas Safe engineer required · £90-160
F.01
Your boiler has stopped working because one of its internal temperature sensors is unable to send a signal to the main control board.
Gas Safe engineer required · £90-180
F.10
Your boiler has detected an electrical fault with the internal temperature sensor that monitors the outward flow of water, causing the system to shut down for safety.
Gas Safe engineer required · £120-£220

All 26 fault codes

Code Severity Plain English
F.00 High Your boiler has stopped working because it can no longer accurately measure the temperature of the water leaving the unit due to a sensor or wiring fault.
F.01 High Your boiler has stopped working because one of its internal temperature sensors is unable to send a signal to the main control board.
F.10 High Your boiler has detected an electrical fault with the internal temperature sensor that monitors the outward flow of water, causing the system to shut down for safety.
F.11 High Your boiler has stopped working because a sensor that monitors the temperature of the water returning to the unit has detected a short circuit.
F.20 High Your boiler has switched itself off because it has become too hot internally, usually due to a lack of water flow or a blockage.
F.22 High Your boiler has detected that there is not enough water pressure or flow to operate safely and has shut down to prevent overheating.
F.23 High Your boiler has detected that the water isn't moving through the system correctly, causing it to heat up too quickly and shut down for safety.
F.24 High Your boiler is heating up too quickly because water isn't moving through the system properly, causing it to shut down to prevent overheating.
F.27 High Your boiler has detected a flame when there shouldn't be one, which has caused it to shut down for safety.
F.28 High Your boiler is failing to light because it isn't receiving gas or the ignition system isn't creating a spark.
F.29 High Your boiler has lost its flame while running and cannot restart, likely because it is not getting enough gas or the ignition system is failing.
F.32 High Your boiler has stopped working because the internal fan isn't spinning at the correct speed to safely clear away exhaust fumes.
F.33 High Your boiler has stopped working because it cannot confirm that harmful exhaust fumes are being safely cleared away through the flue pipe.
F.37 High Your boiler has stopped working because the fan that clears exhaust gases is not spinning at the correct speed or the sensor that monitors it has failed.
F.41 High Your boiler has lost its memory regarding the type of gas it uses and needs to be reconfigured by a professional to operate safely.
F.42 High Your boiler has stopped working because of a wiring issue or an electrical connection problem inside the main control panel.
F.43 High Your boiler has detected an internal wiring problem or a connection issue that is preventing it from running safely.
F.60 High Your boiler's internal computer has encountered a critical electronic failure and can no longer control the heating process safely.
F.61 High Your boiler's internal computer has encountered a communication error or a serious hardware failure that prevents it from running safely.
F.62 Emergency Your boiler is still detecting a flame even after it has told the gas to turn off, which is a safety conflict that causes the system to shut down.
F.63 High Your boiler has detected an internal electrical communication error, which means the main control board is likely faulty and cannot manage the heating process safely.
F.64 High Your boiler has detected an internal electrical glitch or a faulty temperature sensor, causing it to shut down for safety.
F.65 High Your boiler's internal computer has overheated, likely due to an electrical fault or a failing circuit board.
F.66 Medium Your boiler's main control panel is having trouble communicating with the internal display screen, meaning you cannot see or adjust your heating settings.
F.67 High Your boiler's internal computer has encountered a communication error or hardware failure and cannot operate safely.
F22 High Your boiler has stopped working because the water pressure is too low for it to run safely.

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
D.22 Diagnostic Your boiler is currently preparing or delivering hot water, which is a normal operating status of the pre-heat function rather than a failure.
D.24 Diagnostic Your boiler is struggling with water circulation, likely because the internal pump is not working properly or there is an air lock in the system.
S.00 Status Your boiler is currently taking a break because your home has reached the desired temperature or the heating is switched off at the controls.
S.01 Status Your boiler is currently preparing its internal fan to safely start the heating process.
S.03 Status Your boiler is currently going through its routine process of lighting the flame to start heating your water.
S.04 Status Your boiler is operating normally and is currently in the process of heating up after successfully lighting the burner.
S.05 Status Your boiler is currently cooling itself down after a period of operation, which is a normal process and not actually a fault code.
S.07 Status Your boiler is currently running its internal pump to cool down the system after it has finished heating your home or water.
S.08 Status Your boiler is taking a short, programmed break to prevent it from turning on and off too frequently, which protects the system and saves energy.
S.10 Status Your boiler is currently working to provide hot water to your taps or shower, which is a normal status message rather than an actual fault code.
S.14 Status Your boiler is operating normally and is currently in the process of firing up to provide heat or hot water.
S.33 Status Your boiler is struggling to start because it cannot confirm that the fan is pushing enough air through the flue to safely clear fumes.
S.34 Status Your boiler has detected very low temperatures and is running briefly to prevent the internal pipes from freezing.
S.52 Status Your boiler is in a waiting period because the air or flue system has detected a minor issue while trying to start up.
S.53 Status Your boiler has temporarily stopped working because it failed to light or detect a flame correctly after several attempts.

Vaillant Thermocompact is discontinued — time for a new one?

Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.

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