F29On Vaillant boilers, fault code F.29 means: Flame lost during operation. The boiler has locked out for safety. Try the safe checks below and one reset; if the code returns, call a qualified gas engineer.
Can I keep using the boiler?
The boiler has locked out for safety. Try the safe checks below and one reset; if the code returns, call a qualified gas engineer.
Common causes
- Gas supply off or interrupted (closed valve, prepayment meter out of credit)
- Faulty or dirty ignition / flame sensing electrode
- Blocked or damaged flue
- Frozen or blocked condensate pipe
How to fix it
- Check the gas supply is on: gas valve open, meter has credit and other gas appliances work
- Make sure the flue outlet outside isn't blocked (leaves, snow, nests)
- Press the boiler's reset button once and wait for it to restart
- Don't keep resetting: if the code returns, switch off and call a qualified gas engineer
Frequently asked questions
What does Vaillant error F.29 mean?
On Vaillant boilers, fault code F.29 means: Flame lost during operation.
How do I fix Vaillant error F.29?
Start with these steps: Check the gas supply is on: gas valve open, meter has credit and other gas appliances work; Make sure the flue outlet outside isn't blocked (leaves, snow, nests); Press the boiler's reset button once and wait for it to restart; Don't keep resetting: if the code returns, switch off and call a qualified gas engineer.
Is it safe to use the boiler with fault F.29?
Severity: Medium. The boiler has locked out for safety. Try the safe checks below and one reset; if the code returns, call a qualified gas engineer.