High Lockout
E9219 on Worcester Bosch GB162

Your boiler has reached an unsafe temperature and has automatically shut down to prevent damage or overheating.

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

The safety temperature sensor has captured a temperature in excess of 105°C

What causes this fault?

This fault occurs when the water inside the boiler gets too hot too quickly, causing the safety system to shut everything down to prevent damage. The most common reasons are a pump failure that stops water from moving or a blockage in the heat exchanger that traps heat inside the unit. It can also be caused by air trapped in the system or a build-up of sludge restricting the flow.

This fault is often seen when the heating is first turned back on in autumn, as circulation pumps can seize up after being idle throughout the summer.

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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