101 High

Atag 101 Fault Code

The Atag 101 fault code means: your boiler has become too hot and has shut itself down as a safety precaution to prevent damage.. It appears on 2 Atag models 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: Overheat
Typical repair cost £100-350 (including labour)

DIY fix possible

Ensure all radiator valves are fully open to allow water to flow.Check that the boiler pressure gauge is between 1.0 and 1.5 bar; top up if it is too low.Press the Reset button once the boiler has had 30 minutes to cool down.

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Atag models that show the 101 fault code

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

Source

Atag 101 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 7 July 2026