How much does it cost to fix Atag error code A xx?

Cost varies. Contact a Gas Safe registered engineer for a quote.

A xx Low

Atag A xx Fault Code

Q: What does the Atag A xx fault code mean?

Your boiler is currently running a routine air-removal cycle to ensure the system is clear of air bubbles, which is a normal process after a restart or refill.

Also written as AXX — same fault.

The Atag A xx fault code means: your boiler is currently running a routine air-removal cycle to ensure the system is clear of air bubbles, which is a normal process after a restart or refill.. It appears on 7 Atag models in our database.

Technical description: Automatic venting program / de-aeration programm in progress (takes 17 minutes)

DIY fix possible

Wait 17 minutes for the cycle to complete automaticallyEnsure all radiator valves are open to help move air through the systemOnce finished, the boiler should return to normal operation without intervention

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Atag models that show the A xx fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Atag A xx fault code information on this page is sourced and cross-checked against the official Atag service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026