F.62 Emergency

Vaillant F.62 Fault Code

Also written as F62 — same fault.

The Vaillant F.62 fault code means: your boiler has identified a safety issue where the gas valve remains open or is leaking gas when it should be shut off, causing it to lock out for protection.. It appears on 53 Vaillant models in our database.

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description: Flame rectification present 4 secs. after gas valve turns off | Check gas valve, burner tubes and injectors or electronics defect

What causes the Vaillant F.62 fault?

This fault occurs when the boiler's control system detects that gas is still flowing into the burner even after it has commanded the unit to shut down. The most common reason is a mechanical failure where the internal seals of the gas valve become stuck open or the electronic circuit board incorrectly sends power to the valve. Because this represents a significant safety risk, the boiler will immediately stop operating to prevent an uncontrolled flame.

Typical repair cost £250-450 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Vaillant models that show the F.62 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Vaillant F.62 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026