High Lockout
Main burner does not light on Glow-worm Ultimate

Your boiler is failing to ignite the main gas burner, which means you will have no heating or hot water until it is repaired.

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

Check continuity of main solenoid between EV2 and COM. If OK replace multi-functional control. If not OK replace main solenoid.

What causes this fault?

This fault occurs when the boiler's internal components fail to open the gas supply to the main burner after the pilot light has been established. The most common reason is a failed electrical coil within the gas valve, which prevents it from physically pulling open to release fuel for the heating process.

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.

Find a Gas Safe engineer
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