High Lockout
E39 on Remeha Avanta Plus 35c

Your boiler has shut down because a safety sensor has detected that it is getting too hot or that there is an issue with the gas supply pressure.

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

Safety input blocked (e.g. gas pressure switch / heat exchanger thermostat)

What causes this fault?

This fault occurs when one of the boiler's crucial safety sensors detects an unsafe operating condition, such as the heat exchanger reaching an excessive temperature or the gas supply pressure dropping too low. It acts as a protective shutdown to prevent internal damage or unsafe combustion. The most common trigger is either a genuine circulation issue causing the unit to overheat 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

E4View →E13View →

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