Burner locks out with pre-ignition or flame present before start signal
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Critical safety warning: A false flame condition can indicate a leaking gas valve. Turn off gas supply immediately and disconnect power. Do not attempt to restart until the system has been inspected.
Steps (for qualified personnel only):
- Inspect the UV or ionization sensor for damage or contamination. Replace if shorted or cracked.
- Check that no external light source is shining directly into the UV sensor port.
- Verify correct wiring of the flame sensor to the W-FM/WCM control.
- Perform a tightness test on the gas valve train to rule out leakage.
Due to explosion risk, this fault should be handled by a certified Weishaupt technician.
Repair Difficulty
Required Part
We may earn a commission from links on this page.