b24 High

Atag b24 Fault Code

Also written as B24 — same fault.

The Atag b24 fault code means: your boiler has experienced an internal software or brain glitch that is preventing it from running safely.. It appears on 1 Atag model in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Boiler block: Internal error
Typical repair cost £250-450 (including labour)

DIY fix possible

Locate the power switch for the boiler and turn it off.Wait for approximately 30 seconds.Turn the power back on and press the Reset button on the control panel.

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Atag models that show the b24 fault code

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

Source

Atag b24 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