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d.1 on Vaillant ecoMAX

Your boiler is briefly keeping the internal pump running after the heating has switched off to cool down the internal components.

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.

Technical description

Heating system pump over run

What causes this fault?

This occurs because the boiler needs to dissipate residual heat from the internal heat exchanger once the heating or hot water demand has met its target. The system purposefully keeps the pump spinning for a few minutes to circulate water and prevent the internal components from overheating. It is a normal safety function of the boiler's operating cycle rather than a mechanical failure.

DIY fix possible

No action is required as this is a normal operational status code.Wait for a few minutes for the 'd.1' code to disappear automatically.Ensure your radiator valves are open to allow heat to dissipate.

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Related fault codes

d.0View →d.2View →

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