Boiler
E133
The E133 error code on a Baxi boiler indicates an ignition failure — the boiler has tried to light and failed, typically due to a gas supply or ignition system problem. It’s one of the more common Baxi fault codes and can range from a simple fix to a job that requires a Gas Safe registered engineer.
What does this error mean?
When your Baxi boiler displays E133, it means the boiler attempted to ignite and detected no flame within the expected timeframe. The boiler’s control board monitors the ignition sequence and locks out for safety when no flame is confirmed. This is a lockout fault, so the boiler will not attempt to restart automatically until it is manually reset.
Est. repair cost
£100–£250 for professional diagnosis and repair (ignition electrode or flame sensor replacement); new boiler £1,500–£2,500 installed
🔍 Likely causes
🛠️ Step-by-step fix
Check your gas supply first: try lighting a gas hob or another gas appliance. If nothing works, your supply may be interrupted — contact your gas supplier or check your prepayment meter balance before doing anything else.
Check your neighbours: if they also have no gas, report an outage to the National Gas Emergency line on 0800 111 999. Do not attempt to reset the boiler until supply is confirmed.
Press the reset button: if gas supply is confirmed and working, press and hold the boiler’s reset button for 3–5 seconds (location varies by model — check your Baxi manual). The boiler will attempt to re-ignite.
Wait and observe: after resetting, watch and listen for the ignition sequence. If the boiler fires up and runs normally, monitor it over the next 24 hours to see if the fault returns.
If the fault returns after one or two resets, stop resetting. Repeated lockouts can indicate a component fault — continuing to force resets without diagnosis can mask a deeper problem. Call a Gas Safe registered engineer.
Do not attempt to access or adjust the gas valve, ignition electrodes, or PCB yourself. This is illegal without Gas Safe registration and extremely dangerous.
📞 When to call a professional
Call a Gas Safe registered engineer if the E133 code returns after a single successful reset, if the boiler fails to light at all after reset, or if you can smell gas at any point (in which case, evacuate and call 0800 111 999 immediately). When you call, tell the engineer you have a Baxi boiler showing a persistent E133 lockout — this tells them to investigate the ignition electrodes, flame sensor, gas valve, and gas pressure.
⚖️ Repair or replace?
Most E133 repairs — electrode replacement, flame sensor cleaning, or gas pressure adjustment — cost between £100 and £250 with a Gas Safe engineer, making repair the obvious choice for boilers under 10 years old. For boilers aged 10–15 years, weigh the repair cost against a new A-rated Baxi or equivalent boiler, which typically costs £1,500–£2,500 fully installed. If your boiler is over 15 years old and faults are recurring, replacement is almost always the better long-term investment.