Low
D.9 on Vaillant Combi Compact 242EB

Your boiler is receiving a specific temperature instruction from an external control or smart thermostat rather than using its own internal settings.

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

Flow target temperature from external analogue regulator terminal

DIY fix possible

Check your external thermostat or smart home app to see if it is set to a specific temperatureEnsure the external controls are powered on and have fresh batteriesWait to see if the status changes as the external controller reaches its set point

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Related fault codes

D.0View →D.1View →D.90View →

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