If your Potterton boiler has suddenly stopped working and is flashing a fault code, you are not alone. We get calls every week from homeowners who have woken up to no heating or hot water and a mysterious “E” number on the display. The good news is that those codes are designed to help pinpoint the problem quickly.
Whether you need a quick reset or a professional boiler repair service, understanding what the code means is the first step. In this guide, I will walk you through the most common Potterton fault codes, what typically causes them and what you can safely check yourself before calling an engineer.
What Potterton fault codes actually mean
Modern Potterton boilers have built-in diagnostics. When something is not quite right, the boiler locks out and displays a fault code. That code relates to a specific issue, such as low pressure, ignition failure or overheating.
It does not always mean something major has failed. In many cases, especially here in places like Dunmow and Chelmsford where pressure drops are common after bleeding radiators in winter, it can be a straightforward fix.
The key is not to panic. Read the code carefully, note it down and work through the basics before assuming the worst.
How to locate and read the fault code on your boiler
Most modern Potterton models such as the Promax, Gold and Titanium ranges have a small digital display on the front panel. The fault code will usually show as something like E133 or E119.
If your boiler has locked out, you may also see a flashing reset light. Make sure you write the full code down exactly as shown. A single number difference can mean a completely different issue.
If you are not sure which model you have, the name is normally printed on the lower front panel. It helps to know this if you end up speaking to an engineer.
Most common Potterton fault codes and what they mean
E1
On many Potterton models, E1 relates to low water pressure. This is one of the most common call-outs we attend in Harlow, particularly during colder months.
If your pressure gauge is below 1 bar, that is likely your issue. Topping up the system using the filling loop often resolves it.
E2
E2 typically indicates an issue with the temperature sensor. This is not something that can be safely repaired without testing and replacing parts, so it usually requires an engineer visit.
E119
E119 is another low water pressure code. When the system pressure drops too low, the boiler shuts down to protect itself.
Check the pressure gauge. If it is sitting below 1 bar, you can usually repressurise to around 1.2 to 1.5 bar when the system is cold. If it keeps dropping, there may be a leak somewhere in the system.
E125
E125 means the boiler has overheated or the circulation is poor. This can be caused by a faulty pump, airlocks or blockages within the system.
If your radiators have cold spots or you have noticed banging noises before the lockout, that can point towards circulation problems.
E128
This code usually indicates a flame detection fault during operation. In simple terms, the boiler has lost the flame signal while running.
It could be related to the gas supply, the electrode or internal components. This is not one to try and fix yourself.
E133
E133 is a common ignition fault. The boiler has attempted to light but failed.
We often get this after a gas supply interruption or if the meter has recently run out and been topped up. First check that your gas supply is on and other gas appliances are working.
E160
E160 refers to a fan or air pressure fault. The boiler is not detecting correct airflow for safe combustion.
This will always need investigation by a Gas Safe engineer as it involves internal safety components.
Quick DIY checks you can safely try
There are a few things homeowners can check safely before calling for help.
- Check the system pressure and top up if it is below 1 bar
- Reset the boiler once using the reset button
- Make sure the gas supply is on and credit is available if you have a prepayment meter
- Check that the condensate pipe is not frozen during very cold weather
If you reset the boiler and the fault returns straight away, that is a sign there is an underlying issue that needs proper diagnosis.
Never remove the boiler casing or attempt internal repairs yourself. Apart from safety risks, it can also invalidate warranties.
Fault codes that always need an engineer
Any fault relating to ignition, flame detection, overheating or fan issues should be checked professionally. Codes such as E128, E133 that persists after checking gas supply, E160 and sensor faults like E2 fall into this category.
If you are based in Dunmow, Harlow or Chelmsford, it is worth getting it looked at promptly rather than repeatedly resetting it. Lockouts are safety features, not annoyances to override.
I have attended homes where a simple sensor fault left too long ended up causing further wear on other components. Early diagnosis is always cheaper than leaving it.
How to prevent common faults with regular servicing
Many of these fault codes can be avoided with annual servicing. During a service, we check system pressure, test safety devices, clean components and make sure everything is burning correctly.
A boiler that is serviced regularly is far less likely to lock out on a freezing January morning. It also keeps your warranty valid in most cases.
If you are unsure when your boiler was last checked, you can find helpful information on servicing and common questions on our FAQs page.
Can’t clear the fault? Here’s what to do next
If you have tried the safe checks above and your Potterton boiler is still showing a fault code, it is time to get it properly diagnosed.
Make a note of the full fault code, the boiler model and what happened before it locked out. Was the heating on? Had you just topped up the pressure? Those details help speed things up.
If you cannot clear the fault or would simply rather have peace of mind, you can contact us here for advice or to book a visit.
At Harpers Plumbing & Heating, we deal with Potterton fault codes day in and day out across the local area. We will always explain the issue in plain English and talk you through the options so you can decide what is right for your home.
Can’t clear the fault? Call Harpers today.