BoilerFaultCodesAtag 133 Fault Code
The Atag 133 fault code means: your boiler has tried to start several times but cannot light a flame, meaning you will not have any heating or hot water until it is fixed.. It appears on 4 Atag models in our database.
Technical description: No flame after 5 ignition attempts
DIY fix possible
Check if your gas supply is active by testing other gas appliances like a hobEnsure your gas meter has credit if you use a pre-payment meterCheck that the condensate pipe (the plastic pipe leading outside) isn't frozen if the weather is coldPress the Reset button once to see if the boiler restarts
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Gas Safe Register →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 27 April 2026