Boiler Error Codes Explained (Without the Waffle)
Boiler error codes are meant to help engineers… but for normal people they’re basically: “E110” / “F28” / “0A” and a cold flat.
I’m Abdul (Gas Safe 626557). I’ve lost count of how many times I’ve been called to a Newham flat where someone’s
sat staring at a flashing code like it’s going to apologise and fix itself. It won’t. But you can use the code to avoid guessing
and get the right route quickly — emergency vs standard repair.
First: what to do when a code appears (the safe version)
This is the 60–90 second routine I use on the phone. Not DIY repair — just safe triage.
1) Write the code down exactly
Sounds silly until it matters. One letter off and you’re chasing the wrong fault. Take a photo if your hands are full. If it disappears and comes back later, tell me that too.
2) Look for an obvious safety trigger
If there’s any smell of gas, a CO alarm, soot marks around the boiler/flue, or water near electrics — stop and switch route. That’s not the moment to “try one more reset”.
3) Reset once (only once)
One reset is fine on many boilers if it’s locked out. If the code comes straight back, don’t keep cycling it. You’re not “clearing” the fault — you’re just replaying it.
4) Notice what’s missing
Is it no heating, no hot water, or both? Does it start then stop? That context is often more useful than the code alone.
“Hi Abdul — boiler is showing [CODE]. It does [what it tries to do]. We’ve got [no heat/no hot water/both]. Reset once and it [came back / worked briefly / didn’t change].”
Why error codes feel random (and why they aren’t)
In real homes, the boiler’s not operating in a clean lab. You’ve got radiator sludge in older systems, sticky thermostats, dodgy building pressure, and the London “hard water” problem quietly building scale where you can’t see it. Then one cold evening the boiler decides it’s had enough and throws a code.
In Newham we see a weird mix: modern flats with a combi hidden in a kitchen unit, and older terraces with radiators that have clearly been through a few winters. The same error code can show up for different reasons — so the code helps, but it doesn’t replace diagnostics.
Stop DIY and call a Gas Safe engineer if…
Stop DIY and call a Gas Safe engineer if: you smell gas/burning, see soot marks, the boiler repeatedly locks out, or there’s any sign of leaking near electrics.
I know it’s tempting to “just try one more thing”. The problem is: boilers are designed to shut down when something isn’t safe. Let them do that job.
If you want it handled properly (no guessing)
If you’ve got an error code and you’re fed up of the boiler “sort of” working, call 07727 154746. I’ll tell you straight if it’s likely a simple fix, or if it needs a fault-find visit.
Standard route booking is here: boiler repairs & diagnostics.
Bottom line
Error code = information. Not a death sentence. If there are no safety warning signs, book a proper diagnosis and get it fixed correctly. If there are warning signs, switch route to emergency guidance.
Want the bigger picture of what we do? Head back to ARA Services.
FAQ
Do boiler error codes mean I need a new boiler?
Usually not. Most codes point to a fault that can be diagnosed and repaired. Replacement only becomes sensible when the boiler is old, unreliable, or repairs are repeatedly uneconomical.
Is it safe to keep pressing reset until it runs?
One reset is fine. Repeated resets are where people get into trouble — you can stress components and mask a fault. If the code comes back straight away, stop and get it diagnosed.
Why does the code disappear, then come back later?
Intermittent faults happen. Temperature, demand, pressure changes, or a component that’s failing “sometimes” can cause that. If it’s doing that, tell the engineer — it’s a real clue.
Which situations are non-negotiable emergency?
Gas smell, CO alarm, soot marks, or water leaking near electrics. If any of those apply, treat it as urgent. Don’t wait for the code to “change”.
What info should I share when booking a visit?
Boiler make/model, the exact code, and what the boiler does when it tries to run (fires then cuts out, clicking, fan spin, etc.). Also tell us whether you’ve got no heating, no hot water, or both.