E133 Baxi boiler fault

How to Fix an E133 Baxi Boiler Fault: Error Repair Guide

Last updated on June 10th, 2024

The E133 Baxi fault code is shown on the boiler display when there is a problem and your boiler goes to lockout.

I have been carrying out boiler repairs full-time for over a decade and having fault codes on the screen when I arrive is very welcome.

Here I’ll show you how to deal with an E133 Baxi boiler fault based on my on-the-job experiences.

What Does E133 Mean on a Baxi Boiler?

E133 boiler fault

This error code is also used on Main and Potterton boilers (Baxi-owned). Potterton E133 and Main E133 are the same as the Baxi E133 fault.

The E133 fault code meaning according to a Baxi manual:

E133 indicates that the gas supply has been interrupted, ignition has failed or the flame has not been detected.


Here are some of the most common causes from my experiences:

  • Gas Supply Fault: The boiler has been locked out due to not getting any gas. This can be checked quite easily without having to open up the boiler
  • Frozen Condensate Pipe: Another cause for could be a blocked or frozen condensate pipe. If it’s below zero cold weather and you have an external condensate pipe, there is a good chance it has frozen causing your boiler to lockout
  • Faulty Boiler Parts: It could also mean that a part in the boiler is faulty and needs to be replaced, but a lot of the time in my experience it is a gas supply issue

How to Fix E133 Fault

The first thing I would check is that the gas is turned on at the gas meter emergency control valve (ECV).

How to fix E133 on boiler
Emergency control valve turned on

Gas Supply Fault

If you have other gas appliances, like a gas hob or gas fire, then check to see if these are working to find out if you are getting gas in the property.

Prepay gas meter: If you have a prepayment gas meter, make sure you are in credit, as this is quite a common situation I come across.

Gas meter turned off
Gas meter turned off

Frozen Condensate Pipe

If it’s freezing outside, then having a frozen condensate pipe is possible. You can pour hot water on it to melt the frozen condensate water inside the pipe and reset the boiler.

frozen condensate pipe
Frozen condensate pipe

Faulty Boiler Parts

A gas supply problem or a frozen condensate pipe are the most common causes of a Baxi E133 error but it could be caused by faulty boiler parts.

Here are some other potential causes:

  • Faulty gas valve: Might need a new one
  • Worn-out spark electrode: Might need to be cleaned, bent or replaced
  • Faulty PCB (printed circuit board): The PCB is the brain of the boiler and might need to be replaced
Baxi boiler electrode
Baxi spark electrode

How to Reset a Baxi Boiler

The first thing I would do on a Baxi boiler that is not working, no matter what fault code is showing, is to check the pressure and reset the boiler.

This is the simplest way to get your boiler working again, as it might have just locked out.

Modern Baxi Boiler

To reset a modern Baxi boiler (eg 600 or 800), you must find the reset button. This is a button that has ‘Reset’ on it. You have to press the button to reset the boiler.

Sometimes you have to hold it down for a few seconds, but on some Baxis, it just needs to be pressed and released.

Baxi boiler reset button
Baxi boiler reset button

Older Baxi Boiler

If it’s an older Baxi (Duo-tec, 105 etc..) with a knob to turn the boiler on and off, then you will need to turn it fully anti-clockwise and hold it there (at R) until it resets.

How to reset a Baxi boiler
Reset knob on the left

Baxi E133 Won’t Reset

If your E133 error won’t reset, this means you have a problem that needs to be fixed before trying to reset it again.

When the ignition has gone to lockout it won’t reset until the cause of the E133 error is fixed.

If you have fixed a gas supply issue and it still won’t reset, this could mean there is air in the gas pipe.

You should try resetting it a few times to get the gas into the boiler and to get rid of the E133 error code.

Baxi Boiler Guides

Baxi boiler heating


Fixing an E133 Baxi problem is usually done by fixing a gas supply issue. If you have a prepayment gas meter, make sure you put some money on and reset the boiler.

On a cold winter night, an E133 Baxi error is likely to be caused by a frozen condensate pipe. This is easily fixed by pouring hot water over the condensate pipe outside and resetting the boiler.

If you are sure you have gas and the condensate pipe isn’t frozen or blocked, then you should ring a local gas engineer as it could be a gas valve problem.

Feel free to ask me any questions in the comment section below and I’ll try my best to help.

Please share this post if you find it helpful.


How do you clear the fault code on a Baxi boiler?

To clear the fault code on a Baxi boiler, like Baxi E119 boiler fault and E133, you must reset the boiler.

If the fault code appears after resetting the boiler, you will need to find and repair the problem causing your Baxi boiler to lock out and show a fault code.

Why is my Baxi boiler not turning on?

If your Baxi boiler is not turning on at all, and nothing is on the display, then you probably have an electric supply issue.

You need to check the fused spur switch that should be next to the boiler. Make sure it is switched on and the 3 amp fuse is good.

It could also be that the circuit breaker at the main fuse board (consumer unit) has tripped, so you can check there also.


  • Steven Reid

    I am a full-time plumber and Gas Safe registered engineer. I incorporated Housewarm Ltd. in 2011 to provide heating and plumbing services to homes in Newcastle upon Tyne, England. I now blog about what I've learned over the years to help DIYers and plumbers.

    View all posts
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9 thoughts on “How to Fix an E133 Baxi Boiler Fault: Error Repair Guide”

  1. Hi.

    I have a Baxi 105e and I came home to both the spur and 2amp fuse blown.
    The spur has been changed and I have the light however when I changed the 2 amp fuse as soon as the boiler tried to connect to the thermostat after about 15 seconds the fuse blows.

    Is there anything you could help me with at all.
    Many thanks


    1. Steven Reid

      Hi Craig, not much I can tell you but sounds like it could be water in the electrics somewhere, potentially on the PCB or some wiring.

  2. where the white condensate pipe is joined to the boler by a flexible pipe it has split and a small amount of liquid is blown into the boiler,what is the part called,i have a baxi duotec combi 24 he tec

    1. Steven Reid

      It’s called the discharge pipe. Baxi part number 5114763

  3. Mike Wigfield

    Hi Paul
    We have a problem with my stepdaughters Baxi combi boiler the E133 code keeps coming up. I’ve altered the condensate pipe to make sure it has a slope to the outside of the house. I’ve also now fitted a condensate pump But the code still comes up probably about once a day. Once the reset is pushed it resets and works for a while.
    I mentioned it to the service engineer but he said boiler seemed fine and he suggested the pump, but as I’ve said it’s still playing up. Would you think it’s a valve inside the boiler as the gas meter tap seems ok.

  4. Paul Armiger

    I recently had a new smart meter fitted now I’m getting the error code e133 on a baxi duo tec.
    I’ve reset it and ran it for several hours but when it switches on in the morning is when I get the error code and it doesn’t fire up the valve seams to be fully open could it be a faulty meter or just a coincidence?
    Your advice would be appreciated
    Cheers Paul

    1. Steven Reid

      Hi Paul,
      It could be a regulator (at the meter) or another supply problem or just a coincidence. The first thing I’d try to rule out in this weather is a blocked or a frozen condensate pipe issue.

  5. Hi can I ask a question my boiler witch is a main eco combi boiler has had error code E133 twice in a week my boiler due to be serviced in 3 weeks do I need to call an engineer if it happens again

    1. Steven Reid

      Hi Lynne,
      Check the gas valve is fully open at the gas meter (the handle should be in line with the pipe).

      Yes, if it happens again you should probably call an engineer as it could be a problem with not getting enough gas supplied to the house, amongst other things.

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