Baxi Boiler Fault Problems And Cures

The Baxi boiler fault problems and cures Q & A or require an engineer for an emergency boiler repair.

The Baxi Boiler Fault Problems And Cures Common Q & A

Just below, we have a list of common questions relating to the Baxi Boiler.

Baxi Boiler Fault Problem And Cures

Below we’ve created a detail guide to the top Baxi boiler faults, problems and the potential cures. So, if you’re having problems with your Baxi boiler, this guide is going to help.

Your boiler is controlled by a printed circuit board (PCB). It helps all electronic parts work in symphony. And throughout your boiler, there are a range of sensors. These sensors detect things such as heat, flames, water pressure and air pressure.

When the measurements and readings detected by the sensors are outside of the boiler’s working tolerance, the PCB will lock out the boiler. The lock out function on Baxi boilers is designed with one of two things in mind:

  • 1. To protect boiler components from further damage (for instance, the heat exchanger is overheating and could crack)
  • 2. To shut down a boiler that is unsafe to continue operating (for instance, gases aren’t being expelled from the flue correctly)

For these reasons, you shouldn’t try and reset your boiler. If you manage to get the boiler working (for even one minute) before it locks out again, it’s either going to be dangerous, or be causing damage to internal boiler components

Instead you need to speak an emergency boiler repair engineer. They’ll find and fix the fault, and then they’ll be able to reset the boiler on your behalf.

nce the boiler’s locked out, you’ll see a fault code displayed on the control panel. These fault codes provide a Gas Safe engineer with an indication of what the problem might be. It makes the fault-finding mission much quicker.

Here are the most common Baxi boiler fault codes:

If my Baxi boiler is showing the 111 fault code, what does it mean

The 111 fault code on Baxi boilers relates to a flow temperature that’s too high.

The flow is the pipe that takes hot water from your boiler, to be pumped around the heating system. It then returns to the boiler ready to be re-heated and re-circulated via the return. When it returns, it’s going to be a lot cooler.

There are a few possibilities when it comes to what’s causing the flow temperature to be too high. It could be a build-up of limescale, a circulation fault, or even a sensing issue with the PCB or NTC thermistor.

Typically, we’d expect your boiler repair engineer to start with limescale build-up. Limescale comes from minerals in water and is common in “hard” water areas. Where limescale builds-up, components will burn a little hotter than other parts of the system.

If this build-up is near to the NTC thermistor (the part that monitors flow temperature), this could fool the thermistor into thinking the whole heating system is too hot, rather than just the water around the NTC thermistor.

Limescale can be removed using limescale reducing chemicals, and a hot flush. Once this has been done, a boiler specialist can fit a limescale reducer. These reducers act like filters. They’ll be able to catch any loose limescale that passes through them, so it doesn’t settle on boiler components and cause damage.

My Baxi boiler is showing the 117 fault code, why

If you look at your boiler, you’ll notice a pressure gauge. The amount of pressure in your system is directly related to how much water it contains.

The Baxi 117 fault code relates to boiler pressure that is too high. And, when diagnosing the problem, you first need to determine if the pressure is consistently rising with heating on/off, or whether the boiler’s pressure is simply set to high.

If the boiler’s pressure has simply been set too high, water can be drained from the heating system from the drain cock, or radiator bleed valves.

What you’re looking for is a boiler pressure of around 1.3 bar. It will rise naturally when you turn on the heating, but usually by around 0.2-0.3 bar. Anything more than this signifies another fault.

If the boiler consistently increases in pressure, there are a few culprits to look out for.

First, if this happens even when the heating/hot water is off, it’s likely the external filling loop is letting-by water. Essentially, the valve on the filling loop isn’t closing correctly. This will need to be replaced.

Whereby pressure is increasing considerably (0.5 bar or more) causing the 117 fault code to be displayed when the heating is on, the culprit is usually the pressure release valve or expansion vessel. You’ll need to speak to an emergency boiler engineer, and they’ll be able to test both components to determine which one is failing, and then replace that failing part.

They’ll then reset the boiler and check the pressure doesn’t rise to ensure the problem is fixed.

My Baxi boiler is showing the 118 fault code, what does this mean

If your Baxi boiler is showing the 118 fault code, it means that the heating system’s pressure is too low. The amount of water in the system relates to pressure, so it means that the system is lacking water.

The quick-fix is to top up the boiler using the external filling loop. This is small braided hose with a fill valve on it. You’ll want to top up your boiler to around 1.3 bar. Anything above this will be putting excess pressure on internal boiler components.

However, before you top up your boiler, you need to determine why the boiler’s pressure is so low to start with. The pressure of a boiler shouldn’t drop. If it does, there’s a good chance that there’s a leak in the system. And, this leak needs to be found and fixed before you go ahead and top up the pressure.

Typically, you’ll find that leaks come from the boiler itself. Components that are the top culprits include cracked heat exchangers and leaking heating pumps. If the boiler’s pressure is consistently topped up without fixing the leak, the leak could cause further damage by dripping onto electrical components.

If your boiler engineer can’t find a leak in the boiler, they’ll need to inspect towel rails, radiators, copper joints and valves. Even the smallest leak can contribute to a reduction in boiler pressure.

My Baxi boiler is showing the 125 fault code, how can this be fixed

The Baxi boiler 125 fault code relates to a circulation fault. The printed circuit board on your boiler has noticed that water isn’t circulating around the central heating system the way it should be. It’s locking out to protect the pump from burning out, and the heat exchanger overheating.

Circulation faults in boilers can stem from low boiler pressure. The pump struggles to work since there isn’t enough water in the system. So, if your boiler has been displaying the 125 fault code alongside another error code that relates to water/system pressure, there’s a good chance this is the cause of the 125 fault.

The simple fix here would be to ensure that the boiler’s pressure is correct. Your boiler will work best at 1.3 bar. If it’s below this, you can top it up using the external filling loop.

Another probable cause is a problem with the pump itself. A boiler repair engineer will first want to check that the pump is free of air locks, as air locks can restrict water flow.

If it is, they’ll want to check that the pump is installed with the shaft horizontal. If it’s not there’s a good chance that this has led to both the shaft and the shaft’s bearings wearing out immaturely. This is going to mean that the pump can’t work in the way it should.

If the rest of the pump is in good condition, the unit can be reconditioned. However, with pump replacements costing around £250 including parts and labour, it might be worth considering replacing the whole unit.

If everything seems in good condition, and isn’t air locked, your heating engineer will want to check the flow setting on the pump. Most pumps have three flow rate settings. If this is too low for the size of your property, water flow won’t be sufficient, and this will cause the 125 fault code to appear on the display panel.

My Baxi boiler is showing the 128 error code, what does it mean

If your Baxi boiler is displaying the 128 error code on the display panel, the cause is flame loss during boiler operation. This is different to lack of flame (i.e. boiler won’t ignite).

Your Gas Safe boiler repair engineer will want to check a few things after seeing the 128 error code being displayed, including the:

  • Gas valve
  • Electrode, ignition lead and spark generator
  • Burner
  • Flue
  • Gas pressure

Starting with the gas valve, your boiler engineer will want to check that it’s not sticking partially open or closed. If it is, it needs to be freed or replaced. Otherwise, it’s not going to be providing the burner with the correct amount of gas, and that could be dangerous.

Assuming the gas valve is in good condition (after testing for power using a multi-meter), your boiler repair engineer will move onto the electrode, ignition lead and spark generator. Small amounts of debris or moisture build-up on these components can lead to a loss of flame, and the 128 fault code being displayed.

Next, they’ll want to check the flue and burner are clear of debris. It’s unlikely the flue is the cause, unless it’s a vertical flue without a guard fitted. However, the jet in the boiler’s burner is prone to getting blocked with tiny amounts of carbon. This can be cleaned out to fix the problem.

Finally, they’ll want to check the gas pressure into your property (from the meter), and then test again at the boiler. If the gas pressure to your boiler isn’t high enough, it will lock out and display the 128 error code.

My boiler is showing the Baxi 133 error code, can this be easily fixed

The process to figure out what’s caused the 133 error code to be displayed, is similar to the 128 fault code on Baxi boilers. The difference here is there’s likely a gas supply issue that’s not allowing the boiler to ignite, rather than it causing the boiler to fail during operation.

So, the first thing your boiler engineer is going to want to check is that the boiler is getting sufficient gas pressure. They’ll need to highlight the exact point where gas is restricted by testing the gas valve, and the meter.

Typically, the 133 fault code on Baxi boilers is a result of an incorrectly adjusted or faulty gas valve. If it’s adjustment that is the issue, this can be fixed easily. However, if it’s a faulty valve that is sticking so it’s not opening correctly, it may need to be replaced.

As with all issues that relate to electronic components in a boiler (in this case, the gas valve), the printed circuit board can’t be ruled out as the culprit. If the printed circuit board isn’t working correctly, it might not be telling the gas valve to open when it should, and that’s going to mean that gas isn’t being supplied to the burner.

If my Baxi boiler is showing the 160 fault code, what does this mean

If your Baxi boiler is showing the 160 fault code, the problem is with the fan. Unfortunately, there are no specifics attached with the 160 error code, so your Gas Safe heating engineer will need to run tests to find the exact problem.

The fan on your Baxi boiler vents gases out of the flue. These are extremely harmful, so when there’s an issue with the fan, the boiler locks out as a safety precaution.

Your boiler engineer will want to check that the fan’s bearings aren’t worn and causing issues. They’ll also check that the motor is turning freely.

Other checks include the wiring harness, multi-plug and even the PCB. An emergency electrician will be able to test all these electronic components using a multi-meter.

If the result of the test is that the fan is at fault, it will need replacing. Typically, fans are one of the most expensive parts in boilers. If your fan needs replacing, you should expect to pay somewhere in the region of £250.

What does the 162 error code mean on my Baxi boiler, and can it be fixed

The 162 fault code on Baxi boilers relates to an air pressure switch fault.

Your boiler has various sensors monitoring pressures, water flow and temperatures. The job of the air pressure switch is to monitor air pressure within the boiler.

The boiler will only fire up when it receives a signal from the air pressure switch that the fan is operational. It’s the fan that helps to push harmful gases up and out of the flue.

In the case of the 162 fault code, there’s a problem whereby the switch isn’t noticing the fan operating. The printed circuit board receives this signal and either won’t allow the boiler to start or will shut it down completely.

If your boiler engineer finds that the problem is with the air pressure switch, it will need to be replaced. The typical replacement cost including parts and labour is likely to be around £200.

If my boiler is showing a 166 error code, what does it mean

Like the 162 fault code, the 166 error relates to the air pressure switch. It’s likely that a replacement is needed, but various tests can be run to ensure that this is the case.

Your boiler engineer will test the air pressure switch using a multi-meter to ensure it has power. If it hasn’t there’s a chance that loose connections and/or wiring could be the cause of the fault, rather than the switch itself.

Before replacing the switch, it’s important than your boiler engineer figures out what caused the issue in the first place. Typically, the cause will simply be old age. But, another killer of electronic components is water damage. This comes from broken parts such as cracked heat exchangers and leaking pump seals.

If your boiler engineer suspects water damage, they’ll want to find and fix the leak, before fixing/replacing the air pressure switch.

What does the 270 error code mean on my Baxi boiler

The 270 error code on your Baxi boiler relates to a “dry fire”. This happens when the boiler is operating without enough water in the system, or there’s a restriction on water circulation in the boiler.

The boiler locks out in this case, because if it continued to operate, it could damage important components such as the heat exchanger.

If you check your boiler’s pressure gauge (usually located on the front of the boiler’s casing), it’s likely the pressure is well below 1.3 bar. You’ll want to top up the pressure using the external filling loop, a braided hose beneath your boiler.

But, if your boiler keeps losing pressure and displaying the 270 fault code, there’s another problem at hand; it’s likely your system has a leak. You’ll want to contact a qualified heating engineer to find and fix the leak, before topping up your boiler’s pressure.

When a boiler’s pressure drops, that means water is escaping. The question is, where is the leak? This could be leaking on expensive boiler components, floorboards or even plaster. Whatever the case, it’s going to lead to expensive repairs.

If my Baxi boiler is showing the E109 fault code, what does it mean

If the fault code being displayed on the control panel of your Baxi boiler is E109, it’s likely the problem is with the pump; this is a water circulation fault.

Your boiler engineer will want to take apart the pump to determine if this is the problem. A pump’s operation is going to be affected by air locks, sludge build-up and limescale.

And, if the pump’s bearings or shaft are worn, this is going to reduce its ability to circulate water.

If the pump is beyond repair, you should expect a replacement from a leading brand to cost somewhere in the region of £250. Head for brands such as Grundfos or DAB.

If the pump isn’t to blame, another possibility here is that the heat exchanger is blocked with debris. Water flows through the heat exchanger, so if it’s blocked, water circulation is going to be affected. If this is the case, your boiler engineer will be able to remove the debris in the heat exchanger.

However, it’s important to know what that debris is, so preventative measures can be put in place. Typically, we find it’s a combination of limescale and sludge build-up. The best way to combat this build-up is to fit a magnetic boiler filter, scale reducer and dose the system with inhibitor.

The inhibitor will breakdown particles in the heating system. The scale reducing filter and magnetic boiler filter will then both catch these particles, so they don’t pass through the heat exchanger.

My Baxi boiler is showing the 433 fault code, what’s likely to be the problem

If your boiler is showing the Baxi 433 fault code, it’s a problem with the heat exchanger. Once the heat exchanger gets above a certain temperature (95 degrees), the printed circuit board notices there’s a problem, and locks out. In this case, the lock out is to protect the heat exchanger from getting damaged.

The most common cause of the heat exchanger overheating comes from limescale and sludge build-up. This comes from particles in water, as well as rust off the inside of towel rails, radiators and even pipework.

After this breaks off and circulates around the heating system, it starts to get lodged in components, including the heat exchanger. This creates restricted water flow; water can’t escape the heat exchanger quick enough. When this happens, it continues to be heated, and eventually, it’s going to reach 95 degrees at which point the boiler locks out.

The cure, is to have a qualified Gas Safe engineer take apart the heat exchanger. They’ll need to remove the debris from the component, and then refit it. Once done, they can run a hot flush to rid the system of existing sludge/limescale.

They’ll then add two filters; a limescale filter and a sludge filter. By dosing the system with central heating inhibitor these particles will get broken down, and the two filters will be ready to catch them.

Other boiler issues relating to other manufactures

For more boiler issues then please visit the Boiler Problems And Cures page.