What does the Vaillant ecoTEC pro F23 fault code mean?
The F23 fault code on a Vaillant ecoTEC pro boiler indicates a flame failure, meaning the boiler is unable to detect a flame during operation. This can lead to the boiler shutting down to prevent unsafe conditions.
Common Causes
- Gas Supply Issues: Insufficient gas supply or a blockage in the gas line can prevent the boiler from igniting properly.
- Flame Sensor Fault: A malfunctioning flame sensor may fail to detect the flame, causing the boiler to shut down.
Can I fix it myself? (DIY)
It is advisable to call a Gas Safe Engineer for any gas or electrical issues. However, you can check the gas supply and ensure that the boiler pressure is within the recommended range; if low, you may need to repressurise the system.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F23 fault could range from £150 to £300, depending on whether the issue is a simple gas supply blockage or requires replacing the flame sensor, which typically costs around £100 to £200.