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Common Potterton Boiler Problems


Potterton boilers have been around for 100 years. Given that it has survived for so long, it has something to offer UK clients. Though founded in 1850, the company did not become a big deal until the 1930s.

Boilers are convenient and turn your home into a comfortable living space. However, are you having trouble with your boiler making noises? Or probably your radiators have been heating halfway? Whichever the case, you want it fixed fast and well.

What is worse is that the boiler display seems to signal what’s wrong, but you cannot figure out the code. Luckily for you, we’ve pieced together a Potterton boiler common fault code manual along with their fixes.

Note: not all can be done as DIY. For complicated fixes, always hire a Gas Safe engineer.

Faulty Gas Valve Connection (E15 or E09 Fault Code)

The gas valve is controlled by the PCB. It controls the amount of gas flowing into the boiler burner based on the demand for heating and hot water.

When your Potterton boiler displays the E09 or E15 fault code, it means the gas valve connection is intermittent, weak or doesn’t exist. This results in a dangerous gas supply problem. Because of the potential danger, the boiler will lockout.


Unfortunately, there isn’t a DIY solution to the problem. You have to call a Gas Safe engine to test, diagnose and fix the problem.

Usually, it’s the connections and wires that are faulty. But occasionally, we’ve encountered faulty PCB and gas valves which need replacement.

NTC Thermistor Fault

The NTC thermistor monitors the return and flow temperature of the water in the boiler system. They help to ensure that the water isn’t too hot or too cold. Moreover, it ensures certain components of the boiler remain operational.

If the boiler temperature is high, it means there’s an internal problem. For example, when the heat exchanger overheats, it could get weak and crack. A heat exchanger can cost anywhere between £450 along with other water damages.


The Gas Safe engineer will inspect and analyze the PCB and thermistor. Usually, the problem is loose NTC thermistor connections or failure as a result of old age.

The quickest fix is a replacement of the NTC thermistor.

Low boiler pressure

This problem is common with all boiler types and brands. When the boiler pressure is low, your Potterton boiler will lockout and display an E119 error code. This code is specific to the Potterton Profile, Promax, and Suprima boilers. If you have a Potterton Titanium or gold boiler, you’ll see an E118 fault code.

Low boiler pressure is caused by a leak in the system. Leaks come from:

  • Faulty pump seals
  • Cracked heat exchanger
  • A leaking pressure release valve
  • Radiator valves
  • Towel rails
  • Weak soldered joints


Resetting the boiler might get rid of the fault code but it will not solve the problem at hand. Additionally, when the pressure gets to 0.5 bar, the boiler will lockout and will not restart even when you reset it.

Sometimes, adding water to the system will clear the fault code. But if the pressure drops again, it means you have a leak in the system. Hire a Gas Safe engineer to find and seal the leak. The fix might involve re-soldering a joint or replacing a faulty component.

Fan turning on and off

When a boiler turns on, it makes a whirring noise for about 3 seconds before the boiler starts. The whirring sound is from the fan which creates a draught that pushes harmful gases up the flue. The boiler needs to detect the fan is running before it starts.

The PCB receives this signal from the air pressure switch. The air pressure switch measures the internal air pressure and uses the readings to determine if the fan is faulty or not.

If the PCB doesn’t recognize the fan, the boiler will:

  • Not fire up
  • Will cycle on and off as the signal weakens

Since fan fault is caused by a number of problems, the boiler will display either of the following error codes: E131, E152, E151 and E133 (since it can cause ignition fault as well).

However, if it’s a fan fault, you’ll receive an E161 and E160 fault code. The common causes of fan fault include:

  • Damaged or loose wiring
  • Broken PCB
  • Faulty air pressure switch


The Gas Safe engineer will remove the boiler casing and test the fan, PCB, wiring, and air pressure switch using a multi-meter.

The wiring will be repaired and the components might be replaced. However, if the costs exceed £500, we suggest installing a new boiler.

Boiler turns off before the radiators are hot enough

This is a common fault where the boiler heats the radiators but cuts off before the required temperature is attained. In this case, the Potterton boilers display an E20 fault code.

The problem is related to faulty temperature sensors. When the set temperature is attained, they signal the boiler to turn off until the temperature drops and they signal the boiler to turn on.

When the sensors are faulty, they send wrong signals and cut off the boiler before attaining the required temperatures.

The potential causes include:

  • Limescale build-up – when limescale attaches to the boiler components and pipes, some sections burn hotter than others. If the limescale build-up is close to the NTC thermistor, it will be tricked into thinking the set temperature has been achieved.
  • Faulty NTC thermistor – when faulty, they get incorrect readings and send incorrect signals.


Hire a Gas Safe engineer to inspect the NTC thermistor and check the system for limescale build-up. A faulty NTC thermistor can be replaced and limescale can be removed through a Powerflush.

Cold return pipe

When the boiler is switched on, the flow pipe heats up faster than the return pipe. This is because the water coming back to the boiler has lost some heat. As such, a slight differential temperature is expected. If the differential temperature is big, the boiler will display an E193 and E125 and lockout.

The causes of a cold return flow include:

  • A faulty pump – this could be a blown seal or incorrect pump speed setting
  • A blockage in the heating system – the block could be as a result of sludge in the system. A common sign of sludge build up includes radiators that are hot at the top and cold at the bottom.


A Gas Safe engineer will inspect the boiler pump and either set correct speed or replace it. If this does not fix the problem, a Powerflush will work.

No hot water

This is a common problem with the Potterton Suprima, Profile, and Promax boilers. You can have heating but no hot water or have hot water and lack of heating.

This problem is a faulty diverter valve. A diverter valve switches the boiler between hot water and heating operations. With time, it can get stuck in either position. But if the diverter valve is stuck in the middle, the radiators will get hot when a tap and shower are turned on.


The Gas Safe engineer will inspect the diverter valve and replace it. It’s economic and faster to replace than to repair. If the boiler is out of warranty, consider installing a new boiler.

Flame goes out

When the boiler has a flame but loses it after a while, the boiler gives an E129 fault code. It means the boiler can ignite but something is preventing the flame from being sustained. The causes of this include:

  • Blocked condensate pipe (especially during winter)
  • Faulty fan
  • Blocked flue
  • Intermittent gas supply


The Gas Safe engineer will inspect the boiler for any airway blockages. He will also inspect the gas supply for a steady flow. Unblocking the system should fix the problem.

If it’s a faulty sensor or fan, these components will be replaced.

The boiler won’t turn on

Usually, this is a fault with the gas supply. Gas supply problems are caused by a blocked burner or a faulty diverter valve. To ascertain it’s a gas supply problem, inspect other gas appliances. If they work perfectly, then it’s an isolated boiler problem causing the E133 fault code.


The Gas Safe engineer will inspect the gas burner for blockage and the gas valve for mechanical or electrical faults. The gas valve can be freed and the gas burner unblocked or replaced.

Dry fire

A boiler dry fire happens when the boiler system doesn’t have enough water and the cast iron overheats and cracks. It is dangerous and can lead to an explosion.


Add water to the boiler system through the external filling loop. However, if the cast iron has cracked and the boiler is out of warranty, you will have to install a new boiler.

Other fault codes and troubleshooting

Fault code E152– PCB error

How to fix: Replace the PCB.

Fault code E53 – Flue obstruction

How to fix: Unblock the flue

Fault code E109– Poor circulation

How to fix: Bleed and flush the boiler

Fault code E40– NTC thermistor fault

How to fix: Replace thermistors

How to improve your boilers life?

Potterton boiler warranty

Potterton boilers has a wide range of heating solutions with different warranties ranging from 1-7 years. The length of the warranty is subject to registering the boiler on their online platform, conducting annual boiler servicing, and using a Potterton accredited engineer.

Potterton boiler cover

The Potterton boiler cover is recommended for the boilers out of warranty. You’ll pay regular premiums to have your boiler protected in case of a fault or breakdown.

Potterton boiler service

Servicing your Potterton boiler will help keep the boiler efficient and safe. It also helps in maintaining your boiler warranty. The engineer will run boiler tests and conduct a visual inspection to confirm the state of the boiler components.

To get a boiler repair or component replacement, you need a registered boiler engineer. We can provide you with up to 4 affordable quotes you can consider. They are free and from engineers in your location.

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