High Lockout
4.2 on Ideal Logic Max Combi

Your boiler has shut down because its internal temperature has become too high, often caused by a lack of water flow or a blockage.

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

Overheat Lockout

What causes this fault?

This fault occurs when the water inside the boiler gets too hot, triggering a safety sensor to shut the system down to prevent damage. The most common reasons are a pump failure that stops water from moving or a buildup of sludge and debris that creates a blockage in the pipework.

This issue is frequently seen when homeowners turn their heating back on for the first time in autumn, as pump central shafts can seize up after being idle during the summer months.

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

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