Vaillant error codes and what they mean · Luxembourg
All 15 Vaillant fault codes in one table: what each one means, how serious it is and when to call a pro.
| Code | Appliance | What it means |
|---|---|---|
| F.00 | gas boiler | The flow (outgoing) temperature sensor is disconnected or broken. |
| F.01 | gas boiler | The return temperature sensor is disconnected or broken. |
| F.10 | gas boiler | The flow (outgoing) temperature sensor has a short circuit. |
| F.11 | gas boiler | The return temperature sensor has a short circuit. |
| F.20 | gas boiler | The boiler overheated and the safety temperature limiter cut it out. |
| F.22 | gas boiler | The water pressure in the heating system is too low. |
| F.23 | gas boiler | The temperature difference between flow and return is too large, usually because water is not circulating well. |
| F.24 | gas boiler | The boiler temperature is rising too fast, usually because water is not circulating well (air, closed valves or a pump problem). |
| F.25 | gas boiler | The flue gas temperature is too high, or the flue or air supply is faulty or blocked. |
| F.28 | gas boiler | The boiler failed to ignite (no flame was detected) and has locked out. |
| F.29 | gas boiler | The flame went out during operation, or the flame sensor signal is faulty. |
| F.32 | gas boiler | The fan is faulty or is not reaching the correct speed. |
| F.61 | gas boiler | The boiler cannot actuate its gas valve, which indicates a fault in the gas valve assembly. |
| F.63 | gas boiler | The memory chip (EEPROM) on the boiler's control board is faulty. |
| F.75 | gas boiler | The boiler did not detect the expected pressure change when the pump started. |