Baxi Boiler Not Firing Up

Why is My Baxi Boiler Not Firing Up? Most Common Causes

Last updated on February 14th, 2024

Everyone will experience a boiler not firing up at some point.

Your Baxi boiler not working will probably ruin your day, especially on a cold winter’s night.

I have been fitting and fixing boilers full-time for over a decade.

In this post, I’ll show you some of the many boiler problems I come across based on my experiences when I get called to a Baxi boiler not firing up.

Reasons for a Boiler Not Firing Up

There are some very easy fixes for a boiler not firing up.

How to reset a Baxi boiler

Here are some things you can troubleshoot and check yourself:

  • No power supply
  • No gas supply
  • Low boiler pressure
  • Thermostat problems
  • Frozen condensate pipe

No Power Supply

When your boiler is not working and you have no lights on the boiler, there is a good chance you don’t have any electricity to the boiler.

Fused switched spur and fuse
Fused switched spur

Here are some things to check:

  • The fuse in the switched spur next to the boiler (should be 3 amp)
  • The circuit hasn’t tripped at the consumer unit (main fuse board for the house)
  • The fuse in a boiler (usually 2 amp)
  • You have money on a pre-payment electric meter

No Gas Supply

Having your boiler go to lockout when it tries to fire up could mean you don’t have any gas getting to the boiler.

Gas meter turned off
Gas meter turned off

Here are some possibilities:

  • Gas is turned off at the gas meter control valve
  • Gas credit has run out on a pre-payment gas meter

Low Pressure

Low boiler pressure is a very common reason for it not firing up.

Baxi boiler pressure too low

You will need to repressurise the boiler to fix this problem.

Having your boiler pressure low is an easy fix but if your boiler pressure keeps dropping, that means you have a problem that needs to be found and fixed.

Thermostat Problems

A thermostat problem could be the reason your boiler is not working.

Thermostat Problem
Room thermostat

Here are some things you can check:

  1. The thermostat temperature is turned up
  2. The batteries are good (on wireless thermostats)
  3. Faulty thermostat

Frozen Condensate Pipe

A frozen condensate pipe will probably be the reason for your boiler not firing up if it’s below freezing outside.

frozen condensate pipe

When a boiler condensate pipe freezes, the boiler will go to lockout until it has been defrosted.

To defrost a condensate pipe you should pour some hot water over the plastic pipe outside and reset the boiler.

Faulty Parts

Baxi boiler repair

Heating But No Hot Water

Having no hot water from the boiler but the heating is working could be caused by different problem parts.

Combi Boiler

A combi boiler not firing up for hot water could be for one of these reasons:

  • The plate heat exchanger is blocked
  • The diverter valve is stuck or damaged
  • The temperature sensor is broken
  • The flow/micro switch is broken

Heat Only or System Boiler

  • A 2 or 3-port valve is stuck or broken
  • The hot water cylinder thermostat is turned down or faulty
  • The programmer is not working properly

Hot Water But No Heating

When the central heating is not working but the hot water is, there could be many different reasons for this.

Here are some of those reasons:

Combi Boiler

  • The diverter valve is stuck or damaged
  • The room thermostat is turned down, broken, or needs the batteries replaced
  • The temperature sensor is faulty

Heat Only or System Boiler

  • 2 or 3-port valve is stuck or broken
  • The room thermostat is turned down, broken, or needs the batteries replaced
  • The programmer is not working properly

Clicking But Not Igniting

A boiler clicking but not igniting means you are getting electricity, and your external controls are working, so it has to be something further on in the firing-up process that’s causing the problem.

Baxi boiler spark electrode
Baxi boiler spark electrode

Here are some potential reasons why it’s clicking but not igniting:

  1. A gas supply problem
  2. The spark electrode is faulty

Pilot Light Not Firing Up

A boiler pilot light is a constant small flame that is used to light the burner when the heating or hot water is called for.

Modern boilers don’t use pilot lights anymore, they use spark electrodes which fire the boiler up using electric sparks every time it’s needed.

If you have an old boiler with a pilot light and it’s not firing up, here are some potential reasons:

  1. Gas supply problem (blockage or no gas for example)
  2. Gas valve problem

If the pilot light is on but not firing up the boiler, this will usually indicate a faulty gas valve problem.

Baxi Boiler Guides

Baxi boiler Platinum


When your Baxi boiler is not working there are quite a few simple things you can check yourself and rule out without having to open the boiler up.

If you have a radiator not heating up then this will be a radiator problem and not on the boiler.

When it comes to needing boiler parts to be fixed or replaced, you should call a gas engineer to get it checked out properly and fixed.

Regular boiler servicing includes checking boiler parts and should be done every year to help prevent boiler breakdowns.

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.


  • 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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2 thoughts on “Why is My Baxi Boiler Not Firing Up? Most Common Causes”

  1. Bernard Toner

    Good morning
    BAXI combi
    Woke up this morning to no heating – low pressure so sorted that out. However, although the hot water worked fine, the CH ignition light came on briefly but died before actually igniting.
    If there’s no simple answer, I’ll ring the service engineer Monday – just wondered if I’m missing something simple. At least we have hot water!

    1. make sure you haven’t accidentally closed any of the heating valves when increasing the pressure on the boiler.

      you could also try bleeding all the radiators to get rid of any air in the system. make sure to increase the pressure again after bleeding any air out.

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