Potterton Boiler Fault Codes: Full List, Safe Checks and When to Replace

Potterton fault codes are numbers such as E133, E119 or 118 that tell you why the boiler has stopped. Most follow Baxi’s numbering, because Potterton manuals are issued by Baxi Heating UK Ltd, but the low-pressure code changes with the model: E119 on the Gold and Promax HE Plus A, 118 on the Assure and the Potterton 36. Low pressure and the ignition codes are the only ones you can safely look at yourself.

We’re Clever Energy Boilers, a Gas Safe registered (no. 554138) installer based in Bingley and accredited by Worcester Bosch. Over the last 15 years we’ve completed more than 25,000 installations across Yorkshire, the North West and the Midlands. Every code on this page has been checked against the Potterton manuals rather than copied from other lists, and it covers the safe checks, the repair costs and when to stop resetting. An older Potterton that keeps showing faults is usually better replaced with a new boiler, both for efficiency and for saving on repair bills.

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What do Potterton boiler fault codes mean?

Each code points to the part of the boiler that has stopped it, from a sensor to the fan or the gas supply. You may see a code written with or without the E, so E133 and 133 are the same number.

Potterton belongs to the Baxi family. Its manuals are issued by Baxi Heating UK Ltd, Baxi’s trade error-code page lists the Potterton Assure alongside Baxi’s own models, and Assure owners are pointed to Baxi Customer Support. That’s why 110, 125, 133 and 160 mean the same faults on both brands. Our Baxi boiler error codes hub covers the Baxi side.

Which Potterton boiler do you have?

This page covers the Potterton Gold, the Promax HE Plus A and the Assure, all still common in homes around Bradford, Leeds and Halifax. Older non-HE Promax and Performa boilers used indicator lights rather than codes, so check the manual for those. The same goes for any other model, such as the Titanium.

Why do some Potterton code lists disagree?

Because some fault-finder sites get key codes wrong. One popular list calls E125 a flue or air pressure fault and E160 an overheat. The manuals say E125 is a circulation fault and E160 is the fan, and that’s what the tables below follow.

What are the Potterton Gold and Promax HE Plus A fault codes?

These come from the Gold and Promax HE Plus A user manuals. Only E119 and E133 have checks you can safely make at home:

What are the Potterton Assure fault codes?

The Assure shows its codes as plain numbers, and low pressure is 118 here, not 119:

Are Potterton and Baxi fault codes the same?

Mostly. The numbering is shared, so our Baxi guides go deeper on the codes Potterton owners see most. Keep the low-pressure difference in mind:

Is a Potterton fault code dangerous?

The code itself isn’t. It means the boiler has found a problem and shut down rather than carry on.

A gas smell is another matter. Open the windows, don’t use any switches, turn the gas off at the meter and call the National Gas Emergency Service on 0800 111 999. Don’t wait to see whether the code clears.

What can I safely check at home when my Potterton shows a fault code?

A handful of Potterton codes have causes you can rule out yourself. Work through these in order, and leave the casing on:

1. Check the pressure gauge. With the boiler cold, it should read 1 to 1.5 bar. A Gold or Promax shows E119 once it falls below 0.5 bar, and on an Assure you top up if it’s under 0.7 bar. Use the filling loop, watch the gauge climb, then close both valves firmly. Our guide on how to repressurise a boiler shows each step.
2. Is the gas on? For E133, make sure the supply is on and a prepayment meter has credit. If the hob won’t light either, the problem is the supply.
3. Look at the condensate pipe. Baxi says E133, E119 and E128 can all be caused by a frozen condensate pipe. Pour warm water, never boiling, over the frozen section outside. Long pipe runs on exposed walls freeze first, which is worth knowing if you live up on the tops above Keighley or Halifax. Our guide on how to defrost your condensate pipe explains where to look.
4. Reset once and see whether the boiler fires and stays on.

If your Potterton still won’t light, our guide to a boiler not firing up covers the wider picture.

When should I stop resetting a Potterton fault and get a Gas Safe engineer?

As soon as the code comes back after one reset. Get a Gas Safe registered engineer if:

• The code returns straight away
• It’s anything other than the low pressure or ignition and flame codes (E119, 118, E133, 133 and 128)
• Pressure drops again within days of a top-up, which points to a leak
• Water is dripping from the boiler or the pipes below it

Fans, pumps, gas valves, sensors and boards are engineer-only jobs. Never take the casing off yourself.

Why do Potterton fault codes keep coming back?

Usually because a part is wearing out or the system is slowly losing water. A low-pressure code that’s back within days means a leak somewhere, and our boiler losing pressure guide shows where to look. E133 that keeps returning once the gas and condensate pipe are ruled out points inside the boiler. A reset buys you a few days at most.

Is a Potterton fault code a sign you need a new boiler?

On a Gold or Promax, it often is. These are typical UK repair costs for the parts behind Potterton codes:

A sensor on a younger boiler is a fair repair. Age is the bigger question. Most Potterton Gold and Promax boilers still in homes are now over 10 years old, and boilers past 8 years lose a noticeable amount of efficiency. If yours keeps coming back with E133 or E125, you’re likely to be paying for one part after another, and replacing it is usually the cheaper route over time. A PCB fault on an old Potterton is another common tipping point.

Our guide on how to know when your boiler needs replacing lists the warning signs, and our guide to new boiler costs shows what to budget. You can also spread the cost with our boiler finance options.

Replace your old Potterton with Clever Energy

We install Worcester Bosch, Ideal, Vaillant and Baxi boilers in Bingley, Bradford, Leeds, Keighley, Huddersfield, Halifax and across Yorkshire, the North West and the Midlands, all fitted by Gas Safe registered engineers. You can also get a long, market-leading warranty through Clever Energy. See our boiler installation service, or, if you’d like to stay in the same family of boilers, our Baxi boiler installation page. When you’re ready, get your fixed online boiler quote in a few minutes or request a callback. A Clever Care plan keeps the new boiler protected afterwards. If you’d rather talk it through, call 0330 055 2210 between 8am and 8pm on weekdays or 10am to 4pm at weekends.

Potterton boiler fault code FAQs

Is Potterton the same as Baxi?

Pretty much, yes. Potterton manuals are issued by Baxi Heating UK Ltd, Assure owners are sent to Baxi Customer Support, and the code numbers overlap. Low pressure is the main code that differs between models.

What does E133 mean on a Potterton?

The gas supply was interrupted, the boiler failed to ignite, or no flame was detected. Check the gas, your meter credit and the condensate pipe, then reset once. Our Baxi E133 guide covers it in depth.

How do I reset a Potterton boiler?

Once, using the reset button, after checking the pressure, gas supply and condensate pipe. Your user manual shows where it is. If the code returns, leave it for a Gas Safe registered engineer.

Why does my Potterton keep losing pressure?

Water is escaping, either from the system or the boiler itself. A top-up gets the heating back on, but a leak needs an engineer.

Is E118 or E119 the low-pressure code on a Potterton?

Both, depending on the model. The Gold and Promax HE Plus A show E119 below 0.5 bar, while the Assure and the Potterton 36 use 118.

More Potterton and Baxi error codes

Since the numbering is shared, start with our Baxi boiler error codes hub. For individual codes, see the Baxi E133, Baxi E119, Baxi E125, Baxi E160 and Baxi E110 fault code guides.

Other brands are covered in our Glow-worm boiler fault codes, Alpha boiler fault codes and Worcester boiler error codes guides, and our Baxi boilers review looks at the wider brand.