High Lockout
A02 on Ferroli BlueHelix Pro 25C

Your boiler detects a flame when it should be turned off, which prevents the system from starting up 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 signal present with burner off

What causes this fault?

This fault occurs when the boiler's sensors detect a flame signal even though the burner should be currently switched off. The most common cause is a faulty ionisation electrode sending a false signal to the computer, or a gas valve that is failing to close fully and allowing a small amount of fuel to continue burning.

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

A01View →

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