Low
P1 on Zanussi Ultra Combi

Your boiler is displaying a service setting notification rather than a breakdown, indicating the internal pump is being told to run at its maximum speed.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

To set the minimum CH pump speed to 100%

From this model's manual
Verified against the Zanussi Ultra Combi installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This code appears when the installer or a service engineer has manually activated a specific setting within the boiler's menu. It physically forces the internal pump to run at full power constantly for testing or to clear air from the radiators. It is not a hardware failure, but rather a configuration mode that has been left switched on.

DIY fix possible

Press the 'Mode' or 'Reset' button to exit the installer function menuSwitch the boiler off and back on at the main fused spur switchMonitor the display to see if the code clears and returns to the temperature display

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