High Lockout
F.67 on Vaillant Turbomax Plus VUW 242EH

Your boiler's main control board has detected a communication error with its flame sensing system, meaning it cannot safely confirm if the gas 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

Electronic fault | Electronics defect

What causes this fault?

This fault occurs when the boiler's main control board receives an invalid signal from the flame sensing circuitry, causing it to shut down for safety. The most common reason is an internal electronic failure on the Printed Circuit Board (PCB), but it can also be triggered by worn-out electrodes that are no longer able to detect the flame correctly.

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.28View →F.29View →F.61View →F.62View →

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