High Lockout
Test2 on Vokera Pinnacle

Your boiler's internal pump has stopped moving water around the system, which means your heating and hot water will not work.

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

Pump failure

What causes this fault?

This fault occurs when the boiler's internal pump can no longer push water through your radiators or hot water cylinder. The most common reasons are the pump motor seizing up due to age, or a buildup of black sludge and debris from inside your heating system getting stuck in the moving parts.

This issue is most frequent in autumn when the heating is turned back on for the first time, as the pump can seize up after sitting 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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