Boiler fault codes — find your brand and what to do next
A code flashing up on the display tells you roughly what's wrong. Pick your boiler brand below for a plain-English guide to the codes, what's safe to check yourself, and when to call us out.
What a fault code is telling you
Modern boilers watch themselves. When something's not right, the boiler stops and shows a code on the display so you know roughly what's wrong.
Most codes look scary but aren't. Some point to simple things you can sort in a few minutes, like low pressure or a one-off glitch. Others mean a part has failed and needs a Gas Safe registered engineer.
Codes vary between makes and models, so the meaning of the same letters or numbers can differ from one brand to the next. Choose your boiler brand below for the codes that apply to you.
If you ever smell gas, stop everything. Call the National Gas Emergency Service on 0800 111 999, open windows, turn off the gas at the meter, don't touch electrical switches, and leave the property.
Safe checks for almost any boiler
Whatever brand you have, 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.
- 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. Don't keep doing it if the code returns, and never reset an overheat fault.
- If you smell gas, stop everything. Call 0800 111 999, open windows, turn off the gas at the meter, 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 boiler 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 Excellent on Trustpilot. When a fault code won't budge, we'll come and fix it for you.
Boiler fault code FAQs
What do boiler fault codes mean?
A fault code is the boiler's way of telling you why it's stopped. Each code points to a likely cause — low pressure, a sensor fault, ignition trouble or an overheat. The exact meaning depends on your make and model, so pick your brand above and check the code against your manual.
Can I clear a boiler fault code myself?
Sometimes. Simple faults like low pressure can be cleared by topping up via the filling loop. A single reset can clear a one-off glitch. But never reset an overheat fault, and never open the boiler casing — anything involving gas or internal parts needs a Gas Safe registered engineer.
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.
Which boiler brands does Smart Plan cover?
Our boiler module covers most makes, including Worcester Bosch, Vaillant, Ideal and other major brands. 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.
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, don't touch any electrical switches, and leave the property.
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.
Call us today
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2nd Floor, Melrose House
42 Dingwall Road
Croydon
CR0 2NE