F28On Vaillant boilers, fault code F.28 means: Ignition failure, no flame detected. 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)
- Frozen or blocked condensate pipe
- Faulty or dirty ignition / flame sensing electrode
- Faulty gas valve
How to fix it
- Check the gas supply is on: gas valve open, meter has credit and other gas appliances work
- Thaw a frozen condensate pipe with warm (not boiling) water, then reset the boiler
- 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
- If you smell gas: don't use switches, open windows, close the gas valve and call the gas emergency line
Frequently asked questions
What does Vaillant error F.28 mean?
On Vaillant boilers, fault code F.28 means: Ignition failure, no flame detected.
How do I fix Vaillant error F.28?
Start with these steps: Check the gas supply is on: gas valve open, meter has credit and other gas appliances work; Thaw a frozen condensate pipe with warm (not boiling) water, then reset the boiler; 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; If you smell gas: don't use switches, open windows, close the gas valve and call the gas emergency line.
Is it safe to use the boiler with fault F.28?
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.