Fixing an E133 error at home starts with checking your gas supply, meter, and any isolation valves near the boiler, since interrupted gas is the most common cause. If everything checks out and gas is definitely reaching the boiler, resetting it once may clear the fault. If it returns, the cause is likely low gas pressure, a fan fault, or a valve issue that needs a Gas Safe engineer.
A baxi 133 error almost always points to a problem with the gas supply reaching the boiler rather than a fault inside the appliance itself, so the first thing to check at home is whether gas is actually getting through, not whether the boiler needs replacing. Check your gas meter, make sure any isolation valves near the boiler are fully open, and confirm other gas appliances in the house are working normally. If gas supply checks out fine and the code keeps returning, the fault sits further down the ignition chain and needs a proper inspection.
What Does E133 Mean on a Baxi Boiler
E133 is the fault code Baxi boilers show when they detect a loss of gas supply or insufficient gas pressure during the ignition sequence. Rather than attempting to fire with inadequate gas, which risks an unstable flame, the boiler locks out and displays this code as a safety measure. It’s one of the more common Baxi fault codes, and in a large share of cases the actual cause sits outside the boiler entirely, in the gas supply itself.
Checking Your Gas Supply First
Start with the basics before assuming anything is broken. A prepayment meter running low, a supplier outage, or a gas valve near the boiler that’s been knocked or turned off during other work can all trigger E133 with the boiler working perfectly fine otherwise. Walk over to your gas meter and check it’s registering supply, then look at any isolation valve on the pipe running into the boiler and make sure the handle lines up with the pipe, showing it’s fully open.
Quick Test: Are Other Gas Appliances Working?
If you have a gas hob or gas fire elsewhere in the house, check whether that’s working too. If nothing gas-related is working anywhere in the property, the issue is almost certainly at the supply level rather than something specific to the boiler.
Resetting the Boiler Correctly
Once you’ve confirmed gas is flowing normally, locate the reset button, usually marked clearly on the control panel, and hold it for a few seconds until the display changes. Give the boiler a minute to attempt ignition again. A single reset clearing the fault, with no repeat within the next day or two, generally means it was a temporary supply blip rather than an ongoing fault.
1. Confirm gas supply is on and other gas appliances work.
2. Check isolation valves near the boiler are fully open.
3. Press and hold the reset button until the display changes.
4. Wait a few minutes and check whether the boiler ignites and runs normally.
5. Monitor over the next 24 to 48 hours for the code returning.
When the Fault Points to Boiler Flame Failure
If gas supply is confirmed normal and resetting doesn’t hold, the problem shifts from supply to something preventing a stable flame once gas does reach the burner. This is where boiler flame failure comes into play, typically caused by a fan running below the speed the boiler expects, a gas valve not opening consistently, or low gas pressure caused by old or undersized pipework feeding the property. None of these are things to test or adjust yourself, since they involve gas components under pressure.
A Baxi 133 fault that returns repeatedly despite a confirmed, steady gas supply is a strong signal that the issue has moved from an external supply problem to an internal component fault.
Common Causes at a Glance
This table breaks down what typically causes a repeat E133 fault and who’s best placed to deal with it.
| Cause | How It Happens | Who Fixes It |
| Gas supply interruption | Meter runs out, supplier issue, or valve knocked shut | Homeowner checks, reset once resolved |
| Low gas pressure | Old or undersized gas pipework restricting flow | Gas Safe engineer |
| Fan fault | Fan not reaching correct speed before ignition | Gas Safe engineer |
| Gas valve fault | Valve not opening fully or consistently | Gas Safe engineer |
| PCB fault | Control board misreads pressure or timing signals | Gas Safe engineer |
When to Call an Engineer for Baxi Boiler Repair
Call an engineer if the reset doesn’t hold, if E133 returns more than once within a short period, or if you notice a burning smell, unusual noise, or visible damage near the boiler alongside the fault. Baxi boiler repair for E133 issues usually involves testing gas pressure at the appliance itself, checking fan speed against manufacturer specifications, and inspecting the gas valve, none of which can be done safely without the right equipment and Gas Safe registration.
Frequently Asked Questions
1. What does E133 mean on a Baxi boiler?
E133 is the code Baxi boilers display when they detect a loss of gas supply or low gas pressure during ignition. The boiler locks out rather than attempting to fire with insufficient gas.
2. Can I fix an E133 error myself?
Checking your gas supply, meter, and isolation valves is safe to do yourself, and a single reset once supply is confirmed is fine too. Anything involving gas pressure testing or internal components needs a Gas Safe engineer.
3. Why does my Baxi boiler keep showing E133 after I reset it?
Repeated E133 faults after a confirmed working gas supply usually point to a fan fault, a gas valve issue, or low gas pressure at the appliance, all of which need a proper diagnostic visit rather than repeated resets.
4. Is E133 dangerous?
E133 itself is a safety lockout rather than a dangerous state, since the boiler stops attempting ignition rather than running with unstable gas flow. Leaving the underlying cause unresolved for a long period isn’t advisable though.
5. How do I know if the problem is my gas supply or my boiler?
Check whether other gas appliances in the house, like a hob or fire, are also affected. If they are, the issue is with the supply. If only the boiler is affected, the fault is more likely inside the appliance.
6. How long does it take to fix a Baxi E133 fault?
Supply-related causes can be sorted within minutes once identified. Component faults like a fan or gas valve issue typically take a single engineer visit to diagnose and repair.
7. Can cold weather cause an E133 fault?
Indirectly, yes. Cold weather increases demand on the gas network, which can occasionally affect supply pressure, and it also increases boiler usage, which can expose an existing marginal fault sooner.
8. Does E133 mean my boiler needs replacing?
Rarely. Most E133 faults come down to a supply issue or a single faulty component such as a fan or valve, both of which are repairable without needing a new boiler.
9. What’s the difference between E133 and E119 on a Baxi boiler?
E119 relates to low water pressure in the central heating system, while E133 relates to gas supply or gas pressure during ignition. They involve entirely different systems within the boiler despite both being common lockout codes.
10. Why does my boiler lock out only during cold mornings?
This pattern often points to marginal gas pressure that becomes noticeable under higher demand, such as first thing in the morning when heating first fires up after being off overnight.
Final Thoughts
Most E133 faults are more straightforward than they first appear, and working through gas supply and a single reset before assuming the worst saves both time and unnecessary callouts. If the fault keeps returning after those basic checks, that’s the point to stop testing things yourself and bring in someone who can measure gas pressure and inspect the ignition components properly. 0800 Homefix sends Gas Safe registered engineers who diagnose the actual cause of a Baxi 133 fault and get the boiler firing reliably again without guesswork.
