Baxi Boiler 128 Fault Code
The Baxi fault code 128 flame loss Q & A or require an engineer for an emergency boiler repair.
The Baxi Boiler Fault Code 128 Error Common Q & A
Just below, we have a list of common questions relating to the 128 fault code on the Baxi boiler.
- What does the 128 fault code mean on my Baxi boiler?
- What causes my boiler to lose its flame?
- If my Baxi boiler shows a 128 fault code, is it dangerous?
- Can a faulty or incorrectly adjusted gas valve be repaired to clear the 128 error code?
- Will a boiler engineer repair a faulty spark generator, ignition lead or probe?
- How does the burner get blocked with debris, and what problems can it cause?
- Will cleaning the debris from the burner clear the 128 fault code?
- How can the flue cause problems leading to the 128 fault code and a boiler lock out?
- Will an engineer easily be able to recognise a damaged flue?
- What can cause a blockage in a flue?
- What is the condensate pipe and how does it get blocked?
- How can a blocked condensate pipe be fixed?
- What does it mean if my boiler has insufficient gas pressure?
- What are the likely causes of insufficient gas pressure to my Baxi boiler?
- My meter isn’t frozen, but I’ve had a new boiler fitted, what could be causing low gas pressure?
What does the 128 fault code mean on my Baxi boiler?
According to Baxi, the 128 fault code relates to a loss of flame during operation.
What causes my boiler to lose its flame?
There are several potential issues that can cause your boiler to lose its flame during normal operation, including:
- A faulty gas valve, or incorrect adjustment
- Spark generator, electrode or ignition lead fault
- Debris in the burner or jet
- Flue blockage
- Insufficient pressure to supply the appliance with gas
If my Baxi boiler shows a 128 fault code, is it dangerous?
Your boiler will lock out to prevent danger to you, and further damage to internal parts.
This is a signal that you need a professional to find and fix the fault. Once the fault has been isolated and fixed, the boiler can be reset to clear the 128 fault code.
If you smell gas: turn off the mains gas supply, your boiler, and contact a Gas Safe registered engineer.
Can a faulty or incorrectly adjusted gas valve be repaired to clear the 128 error code?
If the gas valve has been deemed faulty, in most cases it makes sense to replace rather than repair it.
A Gas Safe engineer will be able to check the operation of the valve (i.e. it moves freely) as well as the wiring and connections with a multi meter. This ensures it’s communicating correctly with the PCB.
An incorrectly adjusted gas valve won’t need to be replaced.
If the valve has been set in a position whereby when it’s open it doesn’t supply enough gas, this can lead to a flame going out (or fluctuating) during normal operation.
The gas valve will need to be readjusted by a boiler engineer.
Will a boiler engineer repair a faulty spark generator, ignition lead or probe?
All three of these parts are cheap (under £50 depending on your boiler).
By the time you’ve paid for labour, it makes sense to simply replace, rather than recondition these parts.
However, it’s important to isolate the problem to just one of these parts.
A lot of times a fault that might seem obvious (i.e. wiring to the spark generator is faulty) may be linked to a much more expensive fault (i.e. the PCB is faulty and isn’t giving or receiving the correct signals).
Before replacing parts, make sure your engineer finds the root of the problem.
Once the bill gets to over £300 for a repair, it’s worth inspecting all other expensive parts in the boiler (for example: the heat exchanger, PCB, fan and pump).
If these parts also need replacing, the combined replacement cost could be more than the price of a new boiler.
How does the burner get blocked with debris, and what problems can it cause?
Like anything that burns fuel, the burner in your Baxi boiler will get a build-up of debris, such as carbon.
Once debris builds-up in the burner, two things will happen:
- The efficiency of the burner is reduced
- The pilot flame will be weak, unstable, or will fail during operation
Will cleaning the debris from the burner clear the 128 fault code?
A small build-up of debris in the burner will reduce efficiency, but it rarely interrupts the flame in a noticeable way.
What will cause issues is when the jet supplying the flame becomes blocked. These jets are tiny. So, just a few small particles of debris could easily block it, and cause the flame to fail.
These parts are incredibly fragile, but they can be carefully cleaned out. This will help supply the boiler with a stable flame and once the boiler’s been reset, it should clear the 128 fault code.
How can the flue cause problems leading to the 128 fault code and a boiler lock out?
There are a few ways a flue (and its connected parts) can cause a loss of flame signal, and a boiler lock out.
Essentially, if there’s a problem with the flue, the air pressure switch will notice that operating the boiler isn’t safe in current conditions.
The job of the air pressure switch is to feedback this information to the PCB, which will then lock out the boiler.
Issues that can lead to these lock outs include a:
- Damaged or deteriorating flue
- Blockage in the flue
- Condensate pipe blockage
Will an engineer easily be able to recognise a damaged flue?
Although flues are designed to last for a decade or more, they can break apart. A simple inspection of the flue will highlight if the flue has come apart, and is blocking itself.
If the flue has deteriorated due to old age, a replacement will be needed.
What can cause a blockage in a flue?
Flues are open, so anything can get inside and block them. However, it’s extremely uncommon.
The most common blockage is with vertical flues, where the flue goes straight through the roof.
These flues should be fitted with a guard or “bird cage”. This stops anything finding its way into the flue and obstructing it.
If the flue is still in good condition, has a blockage but no guard, your boiler engineer will need to:
- Remove the flue and clear the blockage
- Reinstall the flue
- Install a flue guard
What is the condensate pipe and how does it get blocked?
The condensate pipe is one of the most common boiler problems that occur in winter.
Outside of your property, you’ll notice a thin white pipe (usually 21.5mm in diameter). Most people assume this is their boiler leaking water. But, it’s venting condensed gases from the boiler.
These condensed gases freeze easily. When they do, this causes a condensate pipe blockage and the boiler will lock out.
How can a blocked condensate pipe be fixed?
Most condensate pipe blockages are due to frozen gases.
Slowly thawing out the pipe will remove the blockage. Of course, if the temperatures are still freezing, it’s likely to happen again.
A preventative measure is to use lagging around the pipe.
What does it mean if my boiler has insufficient gas pressure?
Gas pressure can be measured into your gas meter, out of the meter and into your boiler. If any part of the gas run has a lack of pressure, your boiler won’t operate correctly.
In the same way that if the gas valve isn’t providing enough gas and cause flame failure, low gas pressure will do the same.
The boiler’s PCB notices this low gas pressure and will lock out, displaying the 128 fault code.
What are the likely causes of insufficient gas pressure to my Baxi boiler?
During winter, the most common callout for boiler emergencies that relate to gas pressure; is a frozen gas meter regulator.
The regulator on gas meters is the one part that’s the most prone to freezing. When it freezes, it won’t allow sufficient gas into the pipes that feed the boiler, so the gas pressure drops.
The gas meter and regulator need to either be lagged or be boxed-in, so they’re protected from the harshest winter conditions.
My meter isn’t frozen, but I’ve had a new boiler fitted, what could be causing low gas pressure?
Older gas regulations (CORGI and beyond) weren’t as strict as current regulations (Gas Safe).
One potential issue is the gas run itself. If the pipes on the gas run (the circuit of gas pipes supplying the boiler) aren’t big enough, they won’t be supplying enough gas.
If your gas engineer has suggested “upgrading the gas main/gas run”, it’s likely the pipes aren’t supplying enough gas.
In fact, a gas engineer shouldn’t fit a new boiler onto a gas main that doesn’t meet new Gas Safe standards.
This is an issue that only affects around 1/5 properties.
It’s unlikely to be the case if:
- You’ve had a boiler fitted in the last 10 years (the gas main should have been upgraded at time of installation)
- Your property is 10 years old or newer
Other Baxi boiler issues
For more boiler issues regarding the Baxi Boiler then please visit the Baxi Boiler Problems And Cures page.