F.91
Vaillant
Gas Type / Combustion Configuration Error
F.91 gas type / combustion fault; appliance may run roughly or shut down
Advertisements
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.
Advertisements
Possible Causes
Incorrect gas type setting on PCB, Wrong injector set for gas type, Poor combustion adjustment, Blocked burner
How to Fix / Troubleshooting
Safety: Gas type and combustion settings must only be adjusted by a qualified gas engineer.
- Verify gas type: Confirm that the appliance is supplied with the gas type (e.g. natural gas, LPG) for which it is configured.
- Check injectors: Ensure the correct injector set is installed for the gas type.
- Configure PCB: Set the correct gas type and combustion parameters in the PCB service menu according to Vaillant instructions.
- Clean burner: Remove and clean the burner if there is evidence of contamination.
- Combustion analysis: Perform a flue gas analysis and adjust as required within Vaillant’s specified limits.
Advertisements
Repair Difficulty
Professional Required
5/5
Required Part
Burner Injector Set
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements