F10On Vaillant boilers, fault code F.10 means: Temperature sensor (thermistor) fault. 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
- Faulty sensor or component
- Damaged wiring or a loose/corroded connector
How to fix it
- Press the boiler's reset button once and wait for it to restart
- Have a qualified gas engineer inspect the boiler; never open gas or flue parts yourself
Frequently asked questions
What does Vaillant error F.10 mean?
On Vaillant boilers, fault code F.10 means: Temperature sensor (thermistor) fault.
How do I fix Vaillant error F.10?
Start with these steps: Press the boiler's reset button once and wait for it to restart; Have a qualified gas engineer inspect the boiler; never open gas or flue parts yourself.
Is it safe to use the boiler with fault F.10?
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.