High Lockout
62:0 on Viessmann Vitodens 300-W

Your boiler's internal pump has stopped circulating water properly after the burners turn off, which can cause the system to overheat and shut down.

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

Circulation pump without run-on

What causes this fault?

This fault occurs when the boiler's control system detects that the internal pump has stopped spinning immediately after the heat cycle ends, rather than continuing to circulate water to cool the heat exchanger down. The most common reason is a failing pump motor that has developed a dead spot or mechanical resistance, preventing it from performing its crucial post-run cooling phase. In some cases, a communication error from the main circuit board means the pump isn't receiving the command to keep running.

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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