What does the Baxi 133 error code mean?
Baxi fault 133 is an ignition failure: the boiler tried to light and couldn't. It's a close relative of low-pressure warnings but specifically an ignition/sequence fault — check the gas supply, then call an engineer.
What causes the Baxi 133 fault?
The 133 error on a Baxi boiler is most commonly triggered by:
- No or low gas supply (check meter and prepayment credit)
- Dirty or worn spark/ignition electrode
- Frozen condensate blocking the drain in cold weather
- A failing gas valve or ignition control
How to fix the Baxi 133 boiler fault
Follow these steps. If the code returns after you have completed them, stop and call a Gas Safe engineer.
- 1.Verify other gas appliances work; if none do, call your gas supplier or National Gas Emergency on 0800 111 999.
- 2.Reset the boiler once; if 133 returns, stop retrying.
- 3.Book a Gas Safe engineer to inspect the ignition electrode, gas valve and flue.
Frequently asked questions about the Baxi 133
What does fault 133 mean on a Baxi boiler?
133 is an ignition failure — the boiler attempted to light and couldn't. It's usually a gas-supply, electrode or condensate fault and needs a Gas Safe engineer.
Can I reset a Baxi 133 fault?
You can reset once after checking the gas supply. If 133 comes straight back, don't keep retrying — call an engineer; repeated ignition attempts can damage the gas valve.