High Lockout
E9220 on Worcester Bosch GB162

Your boiler has detected an unsafe level of heat or an electrical fault in its safety sensor and has locked down to prevent damage.

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 contacts for the safety temperature sensor have shorted or the safety temperature sensor has detected a temperature higher than 130°c

What causes this fault?

This fault occurs when the boiler's internal safety components detect that the heat exchanger has reached a dangerously high temperature or there is a failure in the electrical sensor that monitors it. The most common reasons are a lack of water flow caused by a pump failure, a heavy build-up of debris in the system, or a faulty sensor sending an incorrect signal to the control 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

E9 219View →E9 224View →

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