High Lockout
HF on Ideal Classic FF

Your boiler has detected a signal for a flame when there shouldn't be one, or there is an electrical fault within the ignition system preventing it from starting safely.

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 DETECTION - SHORT CIRCUIT

What causes this fault?

This fault occurs when the boiler's control system detects an electrical signal suggesting a flame is present before the ignition process has even started. The most common cause is a surge or short circuit in the internal wiring, or moisture buildup on the sensing probe that tricks the system into seeing a 'ghost' flame. Because the boiler cannot verify that it is safe to light, it shuts down as a critical safety precaution.

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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