Potterton boiler fault codes — what they mean and what to do
Seeing an 'E' code flash up on your Potterton? Here's what it's telling you, what's safe to check yourself, and when to call us out.
What a fault code is telling you
Your Potterton boiler keeps an eye on itself. When something's not right, it stops and shows a code on the display so you know roughly what's wrong.
Most codes look alarming but aren't. Some point to simple things you can sort in a few minutes, like low pressure or a one-off ignition glitch.
Others mean a part has failed and needs a Gas Safe registered engineer. We'll always tell you which is which, and we'll never ask you to touch anything to do with gas.
Potterton codes are shown with a letter 'E' followed by two or three digits — for example E133 may flash as 'E1' alternating with '33'. Codes vary a little between Promax, Gold, Titanium and Assure models, so check your manual for the exact wording. The most common ones are below.
Common Potterton fault codes
| Fault code | What it means | What to do |
|---|---|---|
| E110 | Boiler overheat — the safety cut-out has tripped because the boiler got too hot. | Don't keep resetting it. Check pressure and that radiator valves are open, then book a Gas Safe registered engineer. An overheat lockout is a genuine safety trip. |
| E119 | System pressure too low (below about 0.5 bar). | Re-pressurise to about 1.0–1.5 bar using the filling loop, then the boiler should restart. Repeat drops mean a leak — book an engineer. |
| E125 | Primary water circulation fault — water isn't flowing through the boiler properly, often a stuck pump or airlock. | Check the pressure is correct and radiators aren't airlocked. If it persists, book a Gas Safe registered engineer to look at the pump. |
| E133 | Ignition fault — the boiler tried to light but no flame was detected (gas supply, ignition or flame-detection issue). | Check your other gas appliances work and look for a frozen condensate pipe. Reset once. If it returns, book a Gas Safe registered engineer. Smell gas? Call 0800 111 999. |
| E130 / E131 | Flue thermostat fault or lockout — E130 is a flue thermostat fault or flue obstruction; E131 is a flue-thermostat lockout, often after power was lost during a flue fault. | This needs testing. Don't keep resetting — book a Gas Safe registered engineer. |
| E160 / E161 | Fan fault — the fan isn't running at the right speed. | Reset once. If the code sticks, the fan or wiring needs checking by a Gas Safe registered engineer. |
| E20 | Central heating (flow) thermistor sensor fault. | You may still have hot water. Book an engineer to check or replace the sensor. |
| E50 | Domestic hot water sensor fault. | You may still have heating. Book an engineer to replace the hot water sensor. |
| E28 | Flue thermistor (flue sensor) fault. | This isn't a DIY fix. Book a Gas Safe registered engineer to test the flue sensor. |
| E168 / E167 / E151 | Printed circuit board (PCB) fault or lockout — the boiler's main control board has a problem. | Reset once. If it returns, the PCB needs an engineer. Don't keep resetting a board fault. |
| E10 | Outdoor (weather) sensor error, on models fitted with one. | The boiler usually still runs on its standard settings. Book an engineer to check the outdoor sensor or wiring. |
The three codes we get asked about most
E133 — ignition fault / no flame
This is the one most Potterton owners see. The boiler tried to light, couldn't detect a flame, and shut off to stay safe.
First, check your other gas appliances. If the hob won't light either, it could be your gas supply. In cold weather, check the white external condensate pipe isn't frozen — a frozen pipe is a very common cause. Then reset the boiler once, holding the reset for around five seconds.
If E133 comes straight back, stop there. The ignition, flame sensor or gas valve may need a Gas Safe registered engineer. If you smell gas at any point, call 0800 111 999.
E119 — low pressure
This is the friendliest fault to see. Your system pressure has dropped below about 0.5 bar, so the boiler won't fire.
Find the filling loop — usually a silver braided hose under the boiler. Open both valves slowly until the gauge reads between 1.0 and 1.5 bar, then close them fully. The boiler should restart.
If pressure keeps falling after a top-up, you've probably got a small leak somewhere. We'll come and fix it for you.
E110 — overheating
E110 means the boiler got too hot and its safety cut-out tripped. It's doing exactly what it should.
Low pressure, trapped air, sludge or a tired pump can all cause it. Check your pressure gauge and make sure radiator valves are open.
Don't sit there resetting an E110. Repeatedly resetting an overheating boiler can damage the heat exchanger, and the lockout is a genuine safety trip. The heat exchanger or pump may need attention — that's an engineer job.
Safe checks before you call anyone out
These are the only things worth trying yourself. If a code involves gas, skip straight to a Gas Safe registered engineer.
- Check the pressure gauge — it should sit around 1.0 to 1.5 bar when cold.
- Top up via the filling loop if pressure's low, then close the valves fully.
- In cold weather, check the external condensate pipe isn't frozen, and thaw it gently with warm (not boiling) water if it's safe to reach.
- Make sure the boiler has power and the programmer is set to come on.
- Check your thermostat is calling for heat and the batteries aren't flat.
- Confirm your other gas appliances work, to rule out a wider supply issue.
- Reset the boiler once — just once, holding the reset for about five seconds. Don't keep doing it if the code returns, and don't keep resetting an E110 overheat fault.
- If you smell gas, stop everything. Call 0800 111 999, open windows, turn off the gas at the meter control handle (unless your meter is in a cellar or basement), don't touch electrical switches, and leave the house.
When a code won't clear — how Smart Plan helps
If you've checked the simple stuff and the code's still there, the next step is a Gas Safe registered engineer. That's where we come in.
Smart Plan is a service plan, not insurance. You've got two easy options when your Potterton plays up.
Need it fixed now?
Book a one-off repair and we'll come and fix it for you. One of our Gas Safe registered engineers diagnoses the fault and gets your heating back on.
Want cover for next time?
Take out an ongoing Smart Plan boiler module and you're sorted when the next code appears. Parts and labour are included up to your cover limit.
Cover is modular, so you only pick what you want — don't pay for what you don't use. Boiler cover runs up to £500 per year if your boiler's under 7 years old, or up to £200 if it's older. A £95 call-out fee applies.
We've looked after over 15,000 customers, we've been trading since 2014, and we're rated on Trustpilot. When a fault code won't budge, we'll come and fix it for you.
Potterton fault code FAQs
Is boiler cover the same as insurance?
No — it's a service plan, not insurance. You pick the cover modules you want, and when something breaks we send a Gas Safe registered engineer to fix it, with parts and labour included up to your cover limit.
What does E133 mean on a Potterton boiler?
E133 is an ignition fault — the boiler tried to light but didn't detect a flame, so it locked out to stay safe. Check your gas supply works and look for a frozen condensate pipe, then reset once holding the button for about five seconds. If it returns, book a Gas Safe registered engineer. If you smell gas, call 0800 111 999.
How many times should I reset my Potterton boiler?
Just once, and hold the reset for around five seconds. Don't keep resetting an overheat fault like E110 or a PCB lockout. If the same code comes straight back, stop — repeated resets can hide a real fault. Book a Gas Safe registered engineer instead.
Can I fix a Potterton fault code myself?
Only the safe basics — topping up pressure for an E119, thawing a frozen condensate pipe, checking the thermostat, or a single reset. Anything involving gas, the fan, the PCB or internal parts needs a Gas Safe registered engineer. Never attempt a gas repair yourself.
Why does my Potterton keep dropping pressure after I top it up?
If you keep seeing E119 after topping up, it usually points to a small leak in the system. Keep an eye on the gauge and book an engineer to trace it. We'll come and fix it for you.
What should I do if I smell gas?
Call the National Gas Emergency Service on 0800 111 999 straight away. Open your windows, turn off the gas at the meter control handle (unless your meter is in a cellar or basement), don't touch any electrical switches, and leave the property.
Does Smart Plan cover Potterton boilers?
Yes. Our boiler module covers most makes, including Potterton Promax, Gold and Titanium. Cover runs up to £500 per year if your boiler's under 7 years old, or up to £200 if it's older, with a £95 call-out fee.
Code still showing? We'll come and fix it for you.
Book a one-off repair or set up an ongoing Smart Plan boiler module. A service plan, not insurance — parts and labour included up to your cover limit.
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