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Vaillant Boiler F.61 Error Code
Gas valve control fault on Vaillant boilers.
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The electronics that drive the gas valve aren't behaving as expected. Vaillant's UK page puts it down to the control chips not running on time, a wiring fault at the gas valve or a faulty PCB, and the manual adds a short to earth in the harness or valve coils.
Compatible models
Vaillant's UK page lists F.61 without naming models, as does the VU 126 to 356/6-5 OVZ ecoTEC plus manual.
Also shown as
No other codes are listed for this fault.
Difficulty
Try the basic checks, but the usual fix is a technician's job.
Not sure you are reading the code right? See how to read Vaillant boiler codes.
How to fix Vaillant F.61
Reset once and note the code
Hold reset for more than 3 seconds. If it comes back, switch the boiler off and write the code down for the engineer.
When to call a technician
Anything to do with the gas valve or the main board is strictly for a Gas Safe engineer. Smell gas and you leave the house and call the gas emergency line.
Parts linked to F.61
These are the parts an engineer usually checks for this code. They sit inside the sealed casing, so leave them to a Gas Safe registered engineer.
Frequently asked questions
Which Vaillant models show the F.61 code?
Vaillant's UK page lists F.61 without naming models, as does the VU 126 to 356/6-5 OVZ ecoTEC plus manual.
Can I fix Vaillant F.61 myself?
Only the outside checks. The steps above are the ones Vaillant's user instructions allow; if they don't clear F.61, the fix is inside the boiler and needs a Gas Safe registered engineer (RGII in Ireland).
Other Vaillant boiler codes
- F.22Water pressure in the heating system is too low
- F.28Boiler failed to light
- F.29Flame went out and the boiler couldn't relight
- F.20Overheat safety cut-out has tripped
- F.23Too big a gap between flow and return temperature
- F.24Temperature rising too fast
- F.25Flue gas temperature too high
- F.27Flame detected with the burner off
- F.75No pressure rise when the pump starts
- F.00Flow or return temperature sensor not reading
- F.10Temperature sensor short circuit
- F.13Hot water cylinder sensor short circuit
- F.32Fan speed out of range
- F.62Flame took too long to go out
- F.68Unstable flame
- F.70Invalid device code after a repair
- F.83Dry fire: no temperature change when the burner lit
Last reviewed 2026-10-21. Codes and steps can vary by model; check your owner's manual.