Low
D.1 on Vaillant Atmomax

Your boiler is currently cooling itself down after providing heating, which is a normal operating status rather than an actual fault.

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

Water pump overrun – time for heat mode

DIY fix possible

Wait for the timer to finish (usually 2-5 minutes)Check that your room thermostat is not set too highEnsure radiator valves are open to allow heat to dissipate

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Related fault codes

D.0View →D.2View →

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