High Lockout
E83477 on Potterton Powermax HE

Your boiler is failing to detect the flame it has lit, causing the system to shut down for safety.

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

Ionization Lead

What causes this fault?

This fault occurs when the boiler's control system loses the electrical signal used to confirm that a flame is actually present inside the burner. The most common cause is a degraded or dirty sensing electrode that can no longer 'see' the fire, or a faulty wiring lead that is failing to carry that signal back to the main circuit board.

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

E02View →A01View →

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