Low
S.20 on Heatline Monza

Your boiler is currently checking its internal water pump to ensure everything is ready to safely start heating your home.

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

Pre-run pump

From this model's manual
Verified against the Heatline Monza 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.

DIY fix possible

No action required; this is a normal status code during start-upWait for the boiler to complete its pre-run sequenceIf the boiler remains stuck on this code, try a simple reset

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