Also shown as:
F64Quick answer
On Vaillant boilers, fault code F.64 means: Control system error. The boiler has locked out for safety. Try the safe checks below and one reset; if the code returns, call a qualified gas engineer.
Smell gas? Don't use switches or flames, open windows, close the gas valve, leave the building and call your gas emergency number. Never open the boiler casing yourself.
Can I keep using the boiler?
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.
Common causes
- Faulty control or motor board
- Unstable mains power or a loose plug/socket
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.64 mean?
On Vaillant boilers, fault code F.64 means: Control system error.
How do I fix Vaillant error F.64?
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.64?
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.
Vaillant boiler fault codes
F.22Water pressure too lowF.28Ignition failure, no flame detectedF.29Flame lost during operationF.25Flue (exhaust) faultF.32Fan faultF.61Gas valve faultF.73Water level (pressure) sensor faultF.10Temperature sensor (thermistor) faultF.89Pump fault