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Boiler Keeps Turning Off? Lockouts, Error Codes & Common Causes | ARA Services

Boiler Keeps Turning Off?
Lockouts, error codes & what usually causes them

This page is for the annoying one: the boiler fires… then stops. Or it shows an error code, you reset it, and it behaves for ten minutes like nothing happened — then locks out again. We’ll keep this practical (no long theory), and we’ll point you to the right page if your issue is actually frozen condensate or something safety-related.

Call a Gas Safe engineer Book boiler repairs What to do now

If you’re searching “boiler repair near me”, “gas boiler repair near me” or even “emergency boiler repair” because it’s happening right now — do the safe basics once, then stop resetting and get it diagnosed properly.

Don’t troubleshoot if you suspect danger. Gas smell, CO alarm, soot marks around the boiler/flue, or water dripping onto electrics = stop and follow this emergency checklist. If it’s clearly urgent, go straight to emergency boiler help.

First: what a “lockout” actually means (in plain English)

A lockout is the boiler protecting itself. It’s basically saying: “I tried to run, something didn’t look right, so I’m stopping until you reset me.” That “something” could be small… or it could be the start of a bigger failure.

Real-life example: we had a call in East London where the customer had reset it six times in one evening. It would light, run for a bit, then fault out. The actual cause was intermittent ignition (you could see it on testing), and the repeated resets just stressed the system and wasted time. Once we diagnosed it properly, it was a straightforward repair.

Reset once only. One reset is fine. If it locks out again, note the code and symptoms and stop. Repeated resets can make some faults worse (and it makes the diagnosis messier).

What to check safely (no deep DIY, just the basics)

1) Power & controls

Is the boiler actually powered? Is the programmer calling for heat? Is the thermostat turned up? (If it’s a wireless thermostat, check batteries.)

If the display is dead or the fused spur looks damaged, stop and call.

2) Pressure (quick glance)

On many combis, low pressure can trigger lockouts. If the gauge is near 0, the boiler may refuse to run. If you top it up and it drops again soon, that’s not “normal” — it needs diagnosis.

If it keeps dropping, don’t keep refilling. Use: boiler losing pressure causes.

3) Frozen condensate suspicion

If it’s been properly cold and your boiler’s on an outside wall / balcony cupboard, a frozen condensate pipe can cause repeated shutdowns or certain fault codes.

We keep the step-by-step thaw guidance on its own page to avoid overlap: No heating / no hot water quick checks.

4) Look (don’t touch) for water

If there’s water under the boiler or damp around pipework, don’t keep trying to run it. Water + electrics is where things get spicy in the worst way.

Immediate steps live here: boiler leaking — what to do now.

Common causes of lockouts (what we usually find on diagnosis)

These are the patterns we see most when someone says “it runs then stops” or “keeps showing a code”. The exact fault varies by boiler brand, but the categories are pretty consistent.

Ignition / flame detection issues

Boiler tries to light, fails, then locks out. Can be ignition components, flame sensing, gas supply problems, or poor combustion. This is a “test properly” job, not a guessing job.

Overheating / circulation problems

If heat can’t move away from the boiler (sludge, pump issues, blocked parts, air), temperatures spike and safety sensors trip. Often you’ll see it behave, then stop, then behave again.

If it’s also making loud banging/whistling, use: banging / kettling noises.

Sensors / wiring / intermittent electrical faults

These are the frustrating ones: the boiler works, then doesn’t, with no obvious pattern. It can be a sensor drifting out of range, a loose connection, or moisture getting where it shouldn’t. Diagnosis is about proving it with readings, not swapping random parts.

Condensate/flue related shutdowns

Blocked condensate, frozen sections, or issues that affect safe flue operation can lead to shutdowns. If anything suggests a flue safety concern, we treat it seriously and follow the safe route.

Unsure if it’s dangerous? Use: Is this a boiler emergency?

What to write down (this speeds up the repair a lot)

If you want a proper engineer to move quickly, give them clean info. Not an essay — just the useful bits:

Make/model + the exact code

Photo of the boiler front badge and the display code is perfect.

What happens right before it locks out

Does it try to ignite? Any clicking? Any fan noise? Does it run for 2 minutes or 20?

Pressure reading + anything you’ve already tried

One reset? Topped up? Changed thermostat batteries? Good to know — but don’t keep repeating actions.

If you want us to handle it, this is the quickest route: book local boiler repairs or call +44 7727 154746.

If it locks out twice, it’s telling you something

You can’t “out-reset” a genuine fault. If you’ve done the safe basics and it’s still turning off, get it tested properly. For anyone searching local boiler repair or a reliable boiler repair near me in London: we’ll diagnose, explain, and repair — no guesswork.

Scenario CTA: if it’s happening late and the house is getting cold, call +44 7727 154746. If it sounds like a safety issue, we’ll route you straight to the emergency boiler repair path.

Lockout FAQs (the ones people actually ask)

Why does it work after a reset… then fail again?

Because the reset clears the safety lockout, not the underlying cause. If the fault condition returns (ignition fails, overheating, pressure drops, sensor reads out of range), it will lock out again. One reset is fine; repeated resets usually waste time.

Should I tell you the error code if I call?

Yes — it’s one of the most useful clues. Send a photo if you can. Also tell us what the boiler did right before it stopped (trying to ignite, fan noise, short cycling). That combination speeds diagnosis.

Could a frozen condensate pipe cause error codes and lockouts?

It can, especially during cold snaps if the boiler is on an outside wall. We keep the safe guidance on the triage page: 10 quick checks for no heat/no hot water.

Is a lockout automatically an emergency?

Not always. It can be urgent (no heat) without being dangerous. But if there’s a gas smell, CO alarm, soot marks, or water affecting electrics, treat it as an emergency and use: this safety checklist.

What if I’m renting and the boiler keeps failing?

Keep a written log (dates, codes, photos) and report it promptly. For general guidance on responsibilities, use: landlord vs tenant boiler repairs.