High Lockout
F.67 on Vaillant ecoMAX

Your boiler's electronic control board is having trouble communicating with the flame sensor, meaning the system cannot safely confirm if the burner is lit.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Flame amplifier input/output fault

What causes this fault?

This fault occurs when the boiler's main control board loses the ability to correctly process the signal from the flame sensor. The most common reason is an internal electrical failure on the printed circuit board, though it can also be triggered by damaged wiring or worn ignition electrodes that are no longer detecting the flame properly.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.61View →F.62View →F.63View →F.64View →

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