Low
P.00 on Vaillant Atmomax

Your boiler is currently running a self-cleaning routine to remove trapped air from the pipes and is not actually reporting a hardware 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

The heating circuit and hot water circuit are purged

DIY fix possible

Wait approximately 6 to 10 minutes for the program to finish automaticallyEnsure all radiator valves are fully open to help air escapeCheck the pressure gauge and top up to 1.5 bar if it has dropped during the process

Find a Gas Safe engineer
Search the official register →

Related fault codes

P.01View →P.06View →F.22View →

Related guides you might find useful

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →

New boiler cost 2026

Realistic UK prices for a swap.

Read →