Baxi E133 Fault Code: Causes, Fixes & Repair Costs
What does the Baxi E133 fault code mean?
Gas supply fault — the boiler failed to light or lost the flame during ignition and has locked out.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- No or low gas supply Common
The most common cause — gas turned off at the meter, a prepay meter out of credit, an isolation valve closed, or low gas pressure.
- Frozen condensate pipe Common
In freezing weather a blocked condensate pipe can stop the boiler firing and produce an E133 lockout.
- Ignition or flame-detection fault Sometimes
Faulty ignition leads, electrodes or a flame-sensing probe can prevent the boiler detecting the flame.
- Faulty gas valve or PCB Rare
A failing gas valve or printed circuit board can cause repeated ignition failure.
How to fix it
- Check your gas supply. DIY safe
Make sure other gas appliances work, the meter has credit, and the gas isolation valve under the boiler is open.
- Check the condensate pipe for ice. DIY safe
If the external pipe is frozen, thaw it with warm (not boiling) water.
- Reset the boiler. DIY safe
Hold the reset button to clear the lockout. Avoid repeated resets — 2 or 3 attempts is enough.
- Call a Gas Safe registered engineer. Gas Safe engineer
If E133 persists, the ignition components, gas valve or PCB need inspection by a Gas Safe engineer.
Parts you may need
- Ignition electrode · from £25
- Gas valve · from £150
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £80–£450, depending on the underlying cause.
Frequently asked questions
What does E133 mean on a Baxi boiler?
E133 is a gas supply / ignition fault — the boiler couldn't establish or detect a flame and locked out for safety.
Is E133 something I can fix myself?
You can safely check the gas supply and a frozen condensate pipe, then reset. If it keeps returning it's a gas component fault for a Gas Safe engineer.