Low
P.05 on Vaillant Home Combi

Your boiler is currently undergoing an automatic process to refill or bleed internal air, which happens when the system pressure has been adjusted or replenished.

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

Fillingtheproduct: Thedivertervalvemovestothemid-position.Theburnerandpumpswitchoff(tofillordraintheproduct). Ifthepressureislowerthan0.03MPa(0.3bar)andthenisabove0.05MPa(0.5bar)forlongerthan15 seconds,theautomaticpurgingfunctionisactivated. Thefunctionisactivefor15minutes.

From this model's manual
Verified against the Vaillant Home Combi installation & service manual, page 30.
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

Wait 15 minutes for the automatic purging function to complete its cycle.Ensure your system pressure gauge is between 1.0 and 1.5 bar when the boiler is cool.If the code persists, restart the boiler once the 15-minute countdown has finished.

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