High Lockout
Red flashing light on Glow-worm Ci Range

Your boiler has encountered a general operation error and needs to be restarted to resume heating and hot water.

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

Fault occurred. Reset boiler: Turn the On/Off switch to ( 0 ), wait for five seconds. Turn the On/Off switch to ( I ) the boiler is reset.

What causes this fault?

This fault occurs when the boiler's internal computer detects an interruption in the normal operating sequence, causing it to shut down for safety. The most common reasons include a failure to sense a flame correctly or a momentary communication error between the electronic components. If the reset doesn't work, it usually indicates that a part like the ignition lead or the main circuit board is failing to send the correct signals.

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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