This fault can involve incomplete combustion and carbon monoxide.
If anyone in the property feels sick, dizzy or drowsy, or you can smell gas: open the windows, leave the building, and do not switch anything on or off. Then call the National Gas Emergency Service.
0800 111 999Baxi E133 fault codewhat it means and how to fix it
Baxi's ignition lockout: "the gas supply has been interrupted, ignition has failed or the flame has not been detected". Check the gas is on, reset once. If it returns, stop.
Take care
Get a Gas Safe registered engineer to look at your Baxi E133
We do not pass enquiries to a repair firm, so there is no form here. Find a Gas Safe registered engineer through the Gas Safe Register, and ask to see their registration card when they arrive — it is the register, not the van, that tells you they are qualified.
What is the weather doing, and is the gas on elsewhere?
The right answer depends on what you can see. Pick the one that matches.
Choose the option on the left that matches what your appliance is doing, and the answer for that case appears here.
It is freezing outside and the boiler was fine yesterday
Almost certainly the condensate pipe. Baxi name E133 as the frozen-pipe code and say it is a job you can do yourself.
Thaw the outside pipe with warm (not boiling) water or a hot-water bottle, then reset once — selector to R for five seconds, or the button for one to three seconds.
The hob or fire will not light either
No gas at the property. The boiler has done exactly what it should.
Check the meter and any prepayment credit, then call your supplier. Reset once the gas is back.
Gas is on, it is not cold, and one reset has not worked
The fault is inside the boiler: electrode, gas valve setting or the board. Baxi's instruction is to stop and contact your installer or service engineer.
Do not keep resetting. Book a Gas Safe registered engineer.
You can smell gas
Do not reset and do not operate anything electrical.
Turn the gas off at the meter if you can reach it safely, open windows, leave, and call 0800 111 999.
What E133 means
E133 is the code Baxi print on every three-digit generation, and the wording is identical from the 2010 Duo-tec Combi HE A to the 800 Combi: "E133 indicates that the gas supply has been interrupted, ignition has failed or the flame has not been detected." The boiler has sparked for up to five seconds on each of three attempts, seen no flame, and closed the gas valve. On the selector-switch boilers it is shown as E1 alternating with 33 and the Platinum user guide tells the householder exactly two things to do: "Ensure that the gas supply has not been turned off, and turn the selector switch to the reset position and hold for at least 5 seconds. If the boiler does not relight, or the code is displayed regularly contact your installer or service engineer."
On the digital-display boilers the same code carries the R symbol and the reset is the button held for one to three seconds. Baxi's homeowner pages add the winter cause: their frozen-condensate guide says "on most Baxi boilers, the error code will be E133 or E28" and describes thawing the external pipe with warm water before restarting. The steps below are the ones Baxi give the householder and no more, and the limit matters as much as the steps.
Every reset is another three ignition attempts with the valve open, and a boiler that will not light on the second try has a fault an engineer needs to see — an electrode, the gas valve, a gas pressure problem or a flue issue — and repeated attempts on a boiler with a combustion or flue defect are how carbon monoxide gets made. Note also what UK manuals do not show: a second pair of digits after the 133. Non-UK Baxi service tables split the code, but no UK Baxi document read for this page prints a sub-code, and a UK display shows E133 alone.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| No gas reaching the boiler | A prepayment meter out of credit, a gas cock closed after other work, or a supply interruption. Baxi's first instruction is to check the gas has not been turned off, and their user guides suggest checking another gas appliance. | Common |
| Frozen condensate pipe | Baxi's own how-to guide names E133 as the code a frozen condensate pipe produces on most of their boilers. The white plastic pipe outside ices at its lowest point or its open end and the boiler cannot complete a cycle. | Common |
| Ignition or flame-sensing electrode | The 600 Combi fault-finding flow checks the ignition electrode and lead, its connection, and the spark gap and position, then the flame-sensing electrode and its position. The 600 and 800 use a combined detection and ignition electrode, Baxi part 7686344. | Common |
| Gas valve setting or failure | If the burner lights and goes out, Baxi's flow moves to "the set of the gas valve (CO2 values)" before the sensing electrode. A valve that has drifted or a coil that has failed is an engineer-only repair on a sealed component. | Occasional |
| PCB or ignition circuit | Baxi's flow ends at "replace flame sensing electrode or PCB" and "replace PCB" when the electrode and gas valve check out. On the 600 and 800 the spark generator is on the board. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£0–£450
Time on site
1 hour
Thawing a pipe or topping up a meter costs nothing. Detection and ignition electrode (Baxi 7686344) fitted around £110–£180. Gas valve (7683968) £280–£450 fitted. PCB £250–£400.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Parts you may need
We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.
Condensate trap and siphon
COND-TRAP£15–£38Plumbing merchant
Price checked 28 September 2026
Baxi / Potterton / Main detection and spark ignition electrode
7686344£25–£60Authorised Baxi parts distributor
Price checked 28 September 2026
Baxi / Potterton / Main gas valve
7683968£120–£240Authorised Baxi parts distributor
Price checked 28 September 2026
Baxi / Potterton / Main main PCB
£150–£320Authorised Baxi parts distributor
Price checked 28 September 2026
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Baxi fault codes
- E.04.10Get it checkedIgnition failure on the Baxi 200/400 Combi and every Combi 2: the burner would not light after its allowed attempts. Baxi's own quick guide names it the frozen-condensate code you can fix yourself.Related: ignition and gas supply
- E128Get it checkedFlame failure while the burner was running, on the digital-display Baxis. The boiler relights itself unless it keeps happening; Baxi's manuals name gas supply, electrode and flue as the things to check.Related: ignition and gas supply
- E134Get it checkedBaxi's "elapsed time — gas valve open without gas": the valve opened, nothing arrived. Check the meter and credit before anything else; it resets from the panel.Related: ignition and gas supply
- E.01.04Stop — call an engineer"Flame loss detected five times in 24 hours": the burner keeps lighting and going out on a Baxi 200/400 Combi or Combi 2. Gas pressure, valve calibration, flue or electrode — an engineer's list.Related: ignition and gas supply
- E09Get it checkedGas valve connection cable fault on the 600, 800, Compact and Duo-tec 2. The board cannot talk to the valve. Baxi allow one reset; a repeat means the wiring or the PCB.Related: ignition and gas supply
- E135Get it checkedBaxi's "interruption of gas supply (internal error)". Same family as E133 and E134 but the manual calls it internal, so a reset that fails means the board or gas valve circuit.Related: ignition and gas supply
Own a Baxi boiler? Save it and its codes come first next time.
Related guides
Common questions about Baxi E133
How many times can I reset E133?
Baxi's wording is "if the boiler does not relight, or the code is displayed regularly contact your installer or service engineer". Read that as one reset after you have checked the gas is on and thawed the condensate pipe if it is cold. A second failure means an engineer.
Why does the display show E1 then 33?
On the Duo-tec Combi HE, Platinum and Platinum+ the facia has two characters, so Baxi split the code: "code E133 will be displayed by 'E1' alternating with '33'". It is one code.
Does E133 mean the condensate pipe is frozen?
In winter, very often. Baxi's how-to guide says the frozen-pipe code "will be E133 or E28" on most of their boilers. Look for the white plastic pipe leaving the wall behind the boiler and check its outside end and any dips for ice.
Is there an E133 00 or E133 07?
Not on a UK display. Non-UK Baxi service documents split the code into sub-faults, but the UK installation manuals and user guides for every range read for this page print E133 alone, and that is what the boiler shows.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
- Manufacturer support portal
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.