Baxi Boiler 133 Fault Code
The Baxi fault code 133 flame error Q & A or require an engineer for an emergency boiler repair.
The Baxi Boiler Fault Code 133 Error Common Q & A
Just below, we have a list of common questions relating to the 133 fault code on the Baxi boiler.
- What does the 133 fault code mean on my Baxi boiler
- Why isn’t my boiler producing a flame?
- Can this fault be cleared on a DIY basis, by resetting the boiler?
- What causes insufficient gas pressure?
- My engineer says I need to upgrade the gas pipework, is this correct?
- I have a prepayment meter, what could be the issue?
- How will a gas engineer know if the gas valve is broken?
- How can a burner blockage lead to a flame not being detected?
- If the PCB is the component causing the 133 fault, how will the boiler engineer know?
- What else could be causing the 133 fault code to be displayed on my Baxi boiler?
What does the 133 fault code mean on my Baxi boiler?
When a boiler fires up, a flame detection signal is passed on to the PCB (the boiler’s circuit board).
When the 133 fault code is displayed, that’s signifying that the flame has not been detected.
Why isn’t my boiler producing a flame?
The things that cause a weak, incorrect or non-existent flame signal include:
- Insufficient gas pressure
- No credit (prepayment meters)
- Incorrect gas valve adjustment, or faulty gas valve
- Burner blockage
- Communication issues with the PCB
Can this fault be cleared on a DIY basis, by resetting the boiler?
Resetting your Baxi boiler won’t clear the fault. The reset is designed to be used after the problem has been fixed, for safety reasons.
As this is a gas related issue, always contact a Gas Safe engineer to diagnose and fix the problem.
What causes insufficient gas pressure?
In winter months, a common issue with older gas meters is the regulators getting partially or fully frozen.
This gives an intermittent supply of gas. As soon as the boiler recognises this, it will lock out and display the 133 fault code.
The engineer will need to test the gas pressure into the meter, out of the meter and into the boiler. This helps to determine where the fault lies.
For instance, if the low-pressure gas source is from the boiler rather than the meter, there’s a good chance the gas valve is either faulty, or incorrectly adjusted.
My engineer says I need to upgrade the gas pipework, is this correct?
In older properties the gas run (the run of pipes carrying gas) sometimes needs to be upgraded.
Due to newer appliances being more powerful (and newer Gas Safe standards), upgrading pipework to a larger size can sometimes help to solve the issue. If nothing else, it provides your property with a safer supply of gas.
Each property is different, so this will need to be spec’d by an engineer.
As an example, one small gas run may use 22mm/28mm pipe. Another that covers the exact same length may need to be 22mm/28mm & 35mm pipe.
That’s because Gas Safe standards for mains don’t just focus on the run length, but the number of joints too.
I have a prepayment meter, what could be the issue?
A common issue when moving into a new property is having a gas meter that’s in debt.
For example, if a prepayment meter isn’t registered as “not in use” with British Gas, they’ll continue to bill a daily standing charge.
The charge is small (around 27p per day). But if the property has been vacant for a while, any attempt to pay off credit will simply be reducing the previous occupant’s debt.
If you’ve recently moved into a property you need to:
- Contact your utility supplier and ask for a new card key
- Ask them to activate the cards left by the previous owner until the new cards arrive
If you’ve already paid money onto the cards left in the property, utility providers will generally give a refund, or transfer the balance onto the new cards/card keys.
On digital meters, they’ll be able to see the property has been vacant, and any top ups you’ve made on the gas card.
So, have these details ready when contacting them for a refund:
- Move in date
- The address of the store you purchased credit for the card
- Amount of credit purchased
How will a gas engineer know if the gas valve is broken?
Your gas engineer will need to test that the gas valve has full motion, so it can open and close fully when told to by the PCB.
If the operation of the valve seems fine, the engineer will then check the adjustment. Too little gas being provided to the burner, will result in no flame being detected.
A gas valve can cost over £300 to replace, so it’s important to ensure there’s no other expensive repairs left to make.
Even though the gas valve is showing signs of a fault, the PCB needs to be ruled out as a partial culprit too.
Generally, any issues between the gas valve and the PCB, are limited to loose and damaged connections. These can either be repaired or replaced.
However, if the PCB needs replacing, combined with the cost of the gas valve, it might be time to consider a replacement boiler.
How can a burner blockage lead to a flame not being detected?
The burner has a small jet that’s supplied with gas, and creates a flame.
Being so small, it’s easy for the jet to get blocked. Even the smallest piece of grit or dirt could be enough to stop the jet from working.
Luckily, these jets can be removed and cleaned out rather than replaced.
If the PCB is the component causing the 133 fault, how will the boiler engineer know?
Electrical faults are always difficult to diagnose. However, if the 133 fault is linked to the PCB, there’s a good chance you’ve noticed your boiler acting strangely.
The PCB in your boiler communicates with all electronic components. If it gives or receives the wrong signals, then it won’t work how it should.
This could lead to issues including:
- Components cycling on and off for no reason
- Hot water and radiators getting too hot, or not warming up enough
Some newer Baxi boilers will display multiple fault codes at once (or a different code when reset). If the common ground for all these fault codes is an electrical connection to the PCB, then this will need to be investigated thoroughly.
The boiler engineer will be able to test the PCB using a multi-meter. They’ll then do the same for all wires and connections to and from the PCB.
Typically, this will highlight any loose or damaged connections. They can then be replaced or repaired, rather than replacing the whole PCB which could cost more than £400.
What else could be causing the 133 fault code to be displayed on my Baxi boiler?
Besides the most obvious faults mentioned above, there are a few others that could be causing the problem.
The fault code system in boilers isn’t particularly complex. So, the boiler will try to match the fault with the most relevant fault code, but it doesn’t always highlight the exact fault.
In this case, the 133 fault could potentially be caused by anything that gives a spark, flame, or any device that causes a lock out when the tolerances within the boiler are not correct.
This includes:
- The spark generator, ignition lead and probe
- Air pressure switch
A typical example would be the air pressure switch.
This signals to the boiler’s PCB that air pressure within the boiler is within operating range. If it’s not (for instance, due to the fan not being operational), then it will lock out and no flame will be present.
Other Baxi boiler issues
For more boiler issues regarding the Baxi Boiler then please visit the Baxi Boiler Problems And Cures page.