BoilerFaultCodesAtag 133 Fault Code
The Atag 133 fault code means: your boiler is failing to light the gas to create a flame, meaning you will not have any heating or hot water until it is reset or repaired.. It appears on 4 Atag models in our database.
Technical description: No flame after 5 ignition attempts
DIY fix possible
Check that your gas supply is turned on and that other gas appliances (like a hob) are working.Ensure your condensate pipe (the plastic pipe leading outside) isn't frozen if it is very cold weather.Press the 'Reset' button on the boiler control panel once to see if it restarts.
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Atag models that show the 133 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Atag 133 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 31 August 2026