BoilerFaultCodesChaffoteaux 18 Fault Code
The Chaffoteaux 18 fault code means: your boiler has failed to light several times and is trying again, which usually means it is struggling to detect a flame or there is a problem with the gas supply.. It appears on 5 Chaffoteaux models in our database.
Technical description: Attempt to re ignite
DIY fix possible
Check that your gas emergency control valve is in the 'on' positionIf you have a prepay meter, check that you have sufficient creditCheck if other gas appliances, like a hob, are working correctlyPress the Reset button to see if the boiler clears the fault
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Chaffoteaux models that show the 18 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Chaffoteaux 18 fault code information on this page is sourced and cross-checked against the official Chaffoteaux service / installation manuals for each affected model.
- Chaffoteaux Calydra 100 manual (PDF)
- Chaffoteaux Calydra 24 Green manual (PDF)
- Chaffoteaux Talia Green 25 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026