Potterton Boiler Faults, Service And Repairs

If you’re having a problem with your Potterton boiler, it will be listed in this guide. Each section of this guide covers specific fault codes on Potterton boilers, and what you need to do next in terms of servicing and repairs..

When your boiler develops a fault, a code will be shown on the display panel. This helps a Gas Safe repair engineer diagnose the fault quickly, so that repair costs are cheaper than if they had to run a full diagnostic on your boiler.

The code is generated by the boiler’s printed circuit board(PCB). If you know the fault code being displayed on your boiler, you can click the link and read the details on that specific fault code below.

Remember, working on a gas boiler, is a job for Gas Safe qualified repair engineers. If you suspect a problem, trying to fix it on a DIY basis without Gas Safe accreditation or constantly trying to reset your appliance, could put all the people in your property in danger.

Instead of attempting DIY fixes, speak to a boiler repair company instead. They’ll be able to find and fix the fault. They’ll then reset the boiler on your behalf when they’ve fixed the fault.

The Potterton Boiler Fault Code list Common Q & A

Just below, we have a list of common codes related to the Poterton Boiler.

Potterton Boiler Common Error Codes

My Potterton boiler is showing the E09 fault code, what does this mean?

When your boiler displays the E09 fault code, it means there is a problem with the gas valve’s connection to the boiler.

The gas valve is an electronic component, controlled by the PCB. It controls the flow of gas into the burner, and these levels change when you decrease/increase demand for hot water or heating.

When the E09 fault code is displayed, it means that the connection is weak, intermittent, or non-existent. That’s going to cause a gas supply issue that could be dangerous. So, the boiler is likely to lock out, before displaying the fault code.

There’s not a DIY fix for the E09 fault code. You’ll need to call a Gas Safe repair engineer. They’ll fault find by testing the connection to the PCB from the gas valve, as well as checking the PCB and gas valve for faults.

In most cases, it’s wires and connections that are the culprits. However, on some occasions, parts like the PCB and/or gas valve will need to be replaced.

Why is my Potterton boiler showing the E15 fault code on the display panel?

When the E15 fault code is displayed on your boiler, it’s another gas related fault. The gas valve could be giving or receiving the wrong signals, or even sticking partially open/closed when it shouldn’t be.

Typically, the E15 fault code relates to a command fault. That means your boiler engineer is going to be focused on wiring and connections to/from the valve. There’s a good chance that they’ve been damaged.

Damage can occur to these wires from boiler vibrations, water and even old age. Sometimes, the damage is minor. For example, a small connection could have come loose, and re-securing that connection is going to fix the problem.

However, on some occasions, the damage is much more serious. This could lead to a gas valve replacement, that can cost £250-300, depending on the exact type of Potterton boiler that you own.

Can a Potterton boiler showing the E20 fault code be easily fixed?

The E20 fault code on Potterton boilers, relates to an NTC thermistor issue in your appliance. It’s these thermistors that monitor the flow and return temperature of the water in your heating system, as well as water supplying taps and showers.

The idea behind these sensors, is to ensure that water isn’t too hot, or too cold. That’s not just at the point of delivery (for example, radiators or taps) to prevent scalding, but also to ensure all parts in the boiler are operational.

If your boiler’s water temperature is too high, that’s a sign of an internal problem. Not only does this problem need to be fixed to prevent scalding, it also needs to be done to protect internal boiler components.

For instance, if the heat exchanger is overheating, it could weaken and crack. This leak could cause further damage. A replacement could cost £450-500 to install, not to mention the other components that the water damages. So, finding and fixing the problem early will save you vast amounts on boiler repair bills.

Your boiler repair specialist will also need to analyse the components in your boiler such as the thermistors and PCB. Typically, the most likely problem is that the NTC thermistor’s connections have come loose due to boiler vibrations, or the unit has failed due to old age. On most occasions, this is a quick and simple fix; usually, a replacement NTC thermistor is needed.

What is likely to be the cause of the E40 fault code being displayed on my Potterton boiler?

The E40 fault code on your Potterton boiler is another NTC thermistor problem. But, the E40 fault code is specific. It’s the thermistor on the return side (water coming back to the boiler via pipework to be re-heated) causing the problem. The fact that it’s just the NTC thermistor on the return side, helps to narrow down the problem quickly.

If the fault lies with the thermistor, it’s likely the problem stems from a short circuit, faulty NTC thermistor, or the connections between the PCB and thermistor aren’t secure (or, possibly damaged). Your boiler engineer will be able to test this using a multi-meter. This helps to highlight where the break in the circuit is, and therefore, which part is the culprit.

In some cases, we’ve found the problem is electrical, but other contributing factors aren’t helping. They’re causing fluctuations in return pipe temperature, and that’s confusing the PCB. Typically, anything that affects the circulation of water is going to be something your heating repair engineer needs to look at.

This includes:

  • Air locks in the heating system (especially the pump)
  • A pump that’s blocked full of debris, or completely faulty
  • Boiler pressure is too low
  • Blockage in the heating system (such as a radiator, or towel rail)
  • Low output from the heat exchanger

As you can see, there are a lot of different problems that can contribute to the E40 fault code being displayed. The quicker the issue is found and repaired, the more likely it is that a quick and cheap fix is available. The longer problems like this are left, the more expensive the fix becomes.

My boiler is displaying the E83 fault code, what does this mean, and how is it fixed?

When Potterton boilers display the E83 fault code, there’s a problem with room thermostat or timer. Your boiler needs to communicate with the thermostat, to know when you have higher/lower demand for heating. If the device isn’t paired up correctly, is faulty, or isn’t compatible with your boiler, there are going to be issues.

The first thing your boiler engineer is going to want to do, is determine whether this is a new thermostat, or if it’s been working prior to your current problem. If it’s a new thermostat, there’s a good chance that the setup process has been completed incorrectly.

If it’s a particularly old thermostat, it’s likely they’ll test it using a multi-meter. There’s a good chance that old-age has set in, and there’s a problem somewhere in the circuit providing the thermostat with power.

If this is a brand-new timer, your boiler repair engineer will need to check the compatibility of the thermostat. For instance, the ST620WBC from Salus, is designed specifically for Worcester boilers, and not any other brands.

Finally, they’ll want to check the radio frequency you’re running, if you have an RF stat. Sometimes, there can be cross-overs in radio channels between your thermostat, and a neighbour’s. This can cause you to control their boiler, and vice-versa.

Having a boiler or electrical engineer switch the radio frequency channel of the thermostat will fix the problem.

My boiler keeps showing the E110 fault code, how can this problem be fixed?

When a Potterton boiler shows the E110 fault code, it means the maximum temperature gradient has been reached; something is causing your boiler to overheat.

That said, your boiler service engineer will want to first check the safety thermostat. On some occasions, it’s not a physical overheat that’s causing the E110 fault code to be displayed. Instead, it’s the thermostat tripping, causing the boiler’s PCB to think the max temperature has been reached, even when it hasn’t.

Your boiler engineer will be able to test this using a multi-meter. If it is the thermostat that’s tripping, then it’s going to need to be replaced.

However, if the overheat is genuine, your boiler engineer is going to need to focus on anything that affects the circulation of water. This includes checking the pump and heating system for air locks, as well as ensuring the central heating sludge isn’t an issue.

Central heating sludge can block up important components, reduce circulation, and cause overheats. The problem can be fixed by flushing out the system using chemicals, and then fitting a magnetic system filter.

My Potterton boiler is displaying the E118 fault code, what does this mean?

Out of all the Potterton fault codes, the E118 code is one of the most common. The issue that’s causing the fault code to be displayed, is low water pressure.

Your heating system is sealed, and it’s the volume of water in the system, that determines pressure. Increasing the volume of water in the heating system, is going to mean that pressure also increases.

Typically, you’d expect to see a boiler’s pressure to be at 1.3-1.5 bar; that’s optimum working condition for most boilers. If the boiler goes above 3 bar, or below 0.5 bar, it will lock out. The pump will be working too hard to circulate water and could burn out.

The fix here is simple; top up the water pressure by using the external filling loop. If you accidentally top up water pressure to above 1.5 bar, it can be released. You can release water, and therefore pressure, from the drain cock, or from the bleed valves on radiators.

This is a simple DIY fix, but it’s still wise to call an engineer. If your boiler is losing pressure, it’s likely you have a leak. And, if you have a leak, it could be damaging your property (for instance, pipework beneath floorboards, leaking over plaster), or your boiler (for instance, the heat exchanger is leaking onto electrical components).

To avoid expensive long-term repair bills, it makes sense to get an engineer to find and fix any leaks, to stop this (and more problems) happening again.

My Potterton boiler is showing the E125 fault code on the display panel, why?

The E125 fault code on Potterton boilers, is another common one. This is a primary circulation fault. Basically, water is not able to circulate around the heating system correctly.

The first place a boiler repair specialist will start, is the pump. After all, this is what circulates water from the boiler. They’ll be checking for things such as the pump being seized, air locks, and even electrical power. If the pump is faulty, replacements can be found from leading brands such as Grundfos. Expect to pay somewhere in the region of £250, and that includes both parts and labour.

But, there are other common reasons that the E125 is displayed. Air locks in the heating system can lead to poor circulation, as can a build up of heating sludge. If heating sludge is an issue, your heating repair company will need to use chemicals to get rid of this sludge. They’ll then fit a boiler filter, to stop sludge build-up happening in the future.

My boiler tries to fire up, then shows the E128 fault code, why?

If your boiler keeps failing to ignite, it’s likely to show the E128 fault code. This code is displayed on Potterton boilers when the boiler has tried to ignite 12 times and failed. This frequent flame failure is potentially dangerous. The boiler locks out to protect you, and anyone else in the property.

Your boiler engineer will start by checking that the ignition lead and probe are in good condition. It’s likely these are the culprits. If they are faulty, they will need to be replaced by a Gas Safe boiler repair engineer.

But, it’s not always the ignition lead and probe that are to blame. Your boiler needs a clear airway to operate correctly. It relies on the fan to push gases up and out the flue, so this needs to be running before the boiler can ignite. If the fan isn’t working correctly, the boiler will lock out.

Your boiler has an air pressure switch. This switch determines whether the fan is working. So, if the switch is faulty, it’s going to be feeding back the wrong signals to the PCB and lock out the boiler.

And, a steady flow of gas needs to be provided to the burner. If there’s an issue with gas supply from the meter, to the boiler, or in the boiler (the gas valve), this is going to stop the boiler from establishing a flame.

After your boiler engineer has found the problem causing the lock out, they’ll be able to reset the boiler and the fault code will be cleared from the display panel.

What does the E129 fault code mean on my Potterton boiler?

The E129 represents a boiler that had an established flame, but it’s been lost. So, the boiler does have the ability to ignite, but something is stopping the flame from being maintained.

Typically, a boiler servicing and repair company is going to start by checking all airways are clear. That’s going to include checking the flue for debris blockages, and the condensate pipe. In freezing conditions, it’s likely that the condensate has frozen.

All these airways need to be clear. When they’re not, the fan isn’t able to push harmful gases out of the flue. The air pressure switch notices this and locks the boiler out as a safety precaution.

But, the E129 fault code on Potterton boilers isn’t just limited to airway blockages. There could be a problem with the supply of gas.

The first place to start is the burner. The smallest bit of carbon build-up in the jet, will be enough to limit the flow of gas to a point where the flame can’t stay established. Working backwards, your boiler engineer will need to check the gas supply into the burner (i.e. check the gas valve isn’t sticking closed), and the supply of gas into the boiler (i.e. check the meter isn’t blocked or frozen).

If the supply of gas isn’t the problem, it could be a sensing fault. If the boiler’s flame sensor shows no flame, the boiler will shut off. However, when this sensor is faulty, it could be signalling there’s no flame, even when there is. If this is the case, the sensor is going to need to be replaced.

My boiler is displaying the E133 fault code on the display panel, what does this mean?

The E133 fault code on Potterton boilers is a common one. Typically, this is a gas supply issue.

A Gas Safe boiler engineer will be able to narrow down the problem, by checking gas supply to other gas appliances. For instance, if a gas hob, cooker or fire still works, the problem isn’t the gas meter. Instead, they can isolate the problem to boiler.

Like the E129 fault code, the problem usually stems from the burner, or from the gas valve.

If it’s the burner, it’s usually a case of a small amount of debris build-up in the jet. These jets are incredibly delicate, so a tiny spec of debris, could be enough to limit the supply of gas. Cleaning out the jet on the burner, as well as any debris close by, will fix the problem.

If the burner isn’t blocked, your boiler repair company will move onto the gas valve. The gas valve is an electrical, but also mechanical component. And, all mechanical components can wear over time. With gas valves, they tend to stick. In the case of the E133 fault code, it’s likely that the gas valve is stuck closed, even when the PCB is telling it to open.

Sometimes, gas valves can be freed. However, if your gas valve is beyond repair, you’ll need a replacement. Typically, the cost including parts and labour is going to be in the region of £300.

What does the E134 fault code mean on my Potterton boiler?

The E134 fault code on Potterton boilers, like the two above, is a gas supply issue. However, this is a fault that’s directly related to the gas valve.

Potterton state that this fault code occurs when a boiler requests the gas valve to open, but no gas is detected.

And, like the above, it’s likely that the gas valve is stuck closed. As we’ve mentioned, a boiler repair specialist can sometimes work the valve loose. However, they’ll need to be 100% confident that the operation of the gas valve is smooth, so this won’t happen again. If they think the valve needs replacing, it’s likely to cost around £300.

If there seems to be no problem with the gas valve, the next point of call, is the PCB. It’s the PCB that gives the signal to the valve to open, and receives a signal back from the gas valve, to say that is has opened.

If there’s a problem with the PCB, or with wiring and connections to/from it, the signals could be misleading. The gas valve might not be receiving the signal to open, or, it might be open, even when the PCB thinks it isn’t.

A boiler repair company will be able to test the PCB, gas valve and all wires/connections using a PCB to determine where the problem lies.

My boiler keeps showing the E135 fault code, can it be fixed?

The E135 Potterton fault code is another that’s related to the supply of gas. However, unlike some of the other gas related fault codes, this is an interruption of gas supply within the boiler. That’s useful information for your boiler service engineer. That means they can discount problems such as the meter, and gas pipework to the boiler.

The most probable cause here, is the gas valve. It’s common for the wiring and connections between the gas valve and the PCB to be interrupted, so they won’t function in harmony. Typically, we find it’s years of boiler vibrations working these connections loose, or a small level of water damage.

If the connections are simply loose, they can be re-secured to clear the E135 fault. However, water damage is a different story. Whilst wiring and connections can be replaced, your engineer needs to focus on what has caused the leak in the first place.

If they don’t fix the leak causing water damage, this is likely to happen again, not to mention the fact that other parts could get damaged too. Fixing a leak as soon as possible is going to reduce long term boiler repair costs for your boiler.

If the E160 fault code is being displayed, what does it mean and how can it be fixed?

The E160 fault code on Potterton boilers is a fan fault. It’s the fan that keeps your boiler operating safely. It pushes harmful gases from the boiler, out of the flue. In fact, the fan is so important, that the boiler won’t fire up until it gets a signal to say that the fan is operating.

Like all mechanical parts in your boiler, the fan can fail over time. This could be due to old age, faulty wiring, or water damage. Your boiler repair company will be able to determine which of these is the case, by testing the fan with a multi-meter.

On some occasions, this is a simple case of a fan speed that is too low. If that’s the case, the fan can be adjusted, so it creates a big enough draught to push gases out of the flue. The boiler can then be reset to clear the E160 fault code.

If the fan is faulty, it’s going to need replacing. Unfortunately, they’re not cheap components to replace. You should expect to pay somewhere in the region of £250 (the price will vary, depending on the exact boiler model you have).

Can the E163 fault code be fixed on a DIY basis?

The E163 fault code isn’t one that can be fixed on a DIY basis. The problem here is with an NTC thermistor in the boiler. These thermistors monitor the temperature of water, to and from the boiler.

When they notice a temperature differential between the two sensors that is too high or low, they’ll lock out the boiler and display a fault code. Typically, this is to preserve internal boiler components. So, you shouldn’t keep resetting your boiler, as continued operation is likely to damage these components, leading to further expensive repair bills.

The quick fix here, is to have a Gas Safe engineer replace the NTC thermistor. They’ll be able to tell exactly which one is at fault, by testing all NTC thermistors on the boiler using a multi-meter

My boiler keeps displaying the E270 fault code, how can this be fixed?

If your boiler is showing the E270 fault code, that means there’s not enough water in the system. This reduces the pressure in the boiler to a point where it can’t operate. But, it also causes what is known as a dry fire. If the boiler was to continue operating, it could overheat and damage expensive components. So, instead of working, the boiler will lock out, as a self-preservation technique.

Typically, the biggest cause of the E270, is a leak in the heating system. Leaks can come from all sorts of places, including:

  • Radiator and towel rail valves
  • Radiators and towel rails
  • The boiler’s pump or heat exchanger
  • A weak soldered copper joint

Technically, topping up your boiler’s pressure and resetting it, would work as a temporary fix. However, that’s going to mean that the leak hasn’t been fixed. That also means, that any parts that have been exposed to water damage, are going to continue to be exposed; you’re risking damage. So, don’t top up your boiler, until the leak has been fixed by a qualified engineer.

Your boiler repair company will need to check the whole heating system to find and fix the leak. Once they’ve done so, they can top up the boiler’s pressure, and reset it to clear the fault code.

If the boiler continues to lose pressure and the E270 fault code is displayed again, it’s likely that the problem is with the pressure release valve or expansion vessel. It’s rarely worth while fixing them, so a replacement is going to be needed.

What does the E321 fault code mean on my Potterton boiler?

The E321 fault code on your Potterton boiler, means that there’s a fault with the NTC thermistor. The thermistors monitor the temperature of water. This allows the boiler’s PCB to monitor the appliance’s operation. A fluctuation in temperature via the NTC thermistors could indicate a problem, and the boiler locks out.

Typically, the E321 stems from an electrical fault. That’s going to mean that the NTC thermistor has a short circuit or is faulty. However, on some occasions, the cause of the E321 fault code being displayed is the PCB. If the PCB is faulty, the signals it gives and receives are going to be wrong. So, it might not be reading the readings from the thermistor correctly.

Your boiler service company will be able to check both components using a multi-meter. The offending parts will need to be replaced. And, if it’s the NTC thermistor, these are not particularly expensive. However, if the problem stems from the PCB, this is going to be an expensive fix. Typically, a boiler PCB replacement is going to cost in the region of £500.

How can the E384 fault code be fixed on my boiler?

The E384 fault code can be fixed by first, determining the exact cause of the problem. On Potterton boilers, the E384 fault is a false flame. The gas valve should be closed, but the PCB is still detecting a flame.

The most obvious explanation for this, is that the gas valve is faulty. These are mechanical parts, and mechanical parts wear out over time. Valves are known for sticking. They can stick open or closed, but in this case, the valve may be stuck partially open. That’s letting gas into the burner, even when it shouldn’t be.

Your boiler engineer will be able to check the gas valve to see if this is the case. If it is, they’ll attempt to free the valve. On many occasions, this means that a replacement isn’t needed. However, if the gas valve is excessively worn, it makes sense to replace it. A typical gas valve replacement is likely to be in the region of £300.

But, it’s important not to start replacing parts until every possibility has been ruled out. For instance, there could be a problem with the PCB. The PCB has determined that there’s a false flame, but that might be the case.

The valve might be shut, and the flame might not even exist. In this case, the PCB needs to be tested. If it’s the PCB that is faulty, a replacement will be needed. Expect a replacement PCB on a Potterton boiler to be in the region of £500.

Other boiler issues

For more boiler issues regarding any other type of Boiler then please visit the Boiler Problems And Cures page.