Baxi · Duo-tec Combi
E133 boiler fault code
Duo-tec Combi
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What E133 means
E133 indicates a gas supply fault.
Safe check
Do not check the gas supply or attempt internal checks. In cold weather, a frozen condensate pipe is one possible cause on most Baxi boilers. Only thaw an external pipe that is visible and safely reachable from ground level, using warm (not boiling) water. Then try one restart using the boiler instructions.
When to contact an engineer
If the pipe is not safely reachable or the code remains after one restart, stop and arrange diagnosis by a Gas Safe registered engineer.
Safety notice
A boiler fault code alone is not a gas or carbon-monoxide emergency. If you smell gas, a CO alarm sounds, anyone feels unwell, or there is an unsafe flame, leave and call 0800 111 999 from outside.
Source and provenance
- Baxi Professional error-code table · Baxi Duo-tec Combi listing · E133 row
professional error-code table
Checked 30/09/2026; the online table publishes no revision
- Baxi How to thaw a frozen Boiler condensate pipe · steps 1–3, external pipe and restart guidance
homeowner guide
Checked 30/09/2026; the online page publishes no revision
Renting? Report it to your landlord or housing provider first. They are responsible for gas safety and boiler repairs, and the repair should not cost you.
Did this fix it?
After: Thaw the condensate pipe