Boiler ignition lockout means your boiler tried to light, couldn’t detect a flame and has shut itself down until someone resets it by hand. The usual causes are a frozen condensate pipe, a gas supply problem, a worn ignition electrode or flame sensor, a faulty gas valve, a blocked flue or a PCB fault. Each brand shows its own code and has its own rule on resets, so there’s no single number that fits every boiler.
We’re Clever Energy Boilers, Gas Safe registered (no. 554138) and accredited Worcester Bosch installers based in Bingley. Over the last 15 years our engineers have completed more than 25,000 installations across Yorkshire, the North West and the Midlands, and lockout codes are a regular sight once the frosts arrive. This guide covers each brand’s lockout code and reset rule, what causes it, the checks you can safely make and when a new boiler makes more sense than another repair.
What should I do if I smell gas?
Don’t reset the boiler. Turn the gas off at the meter if you can, open doors and windows, avoid light switches and anything else that could spark, and get out of the property. Then call the National Gas Emergency Service on 0800 111 999.
What is boiler ignition lockout?
It’s a safety shutdown, and it means the boiler has done its job. When the heating or hot water calls, the gas valve opens and the ignition electrode sparks. A flame sensor then checks that a flame has lit. If it can’t see one, the boiler shuts the gas off and tries again, and after a set number of failed attempts it stops trying altogether.
That number depends on the boiler. A Worcester Bosch showing EA 227 tries to ignite 4 times, waiting 30 seconds between attempts, before it locks out. The Vaillant ecoTEC plus manual says the boiler won’t operate after 5 failed ignition attempts.
A boiler that shows no sign of trying to light is a different problem. Our guide to a boiler not firing up covers the wider no-start causes. This page deals with the locked-out state itself.
What’s the difference between a locking and a blocking error?
A locking error waits for you. A blocking error doesn’t. HomeServe’s list of Worcester Bosch codes splits faults into these two types:
- Blocking errors stop the boiler, then clear on their own once the cause goes away.
- Locking errors keep it off until someone resets it by hand.
Ignition faults are locking errors. If your boiler sorted itself out after a few minutes, it was probably a blocking error. If it’s sitting there with a code on the display and nothing happening, it’s locked out.
Boiler lockout codes at a glance
Every manufacturer uses its own lockout codes and gives its own advice on resets. Find your brand here:
| Brand | Code | What the code means | Brand’s reset rule |
|---|---|---|---|
| Worcester Bosch | EA 227 | No flame detected after ignition. It tries 4 times, 30 seconds apart, then locks out | No number given |
| Worcester Bosch | EA 229 | Flame lost while running. A blocked condensate trap can cause it | No number given |
| Vaillant | F.28 | No flame during ignition | Reset 3 times, then call a competent person |
| Vaillant | F.29 | The flame went out | Reset 3 times, then call a competent person |
| Ideal | L2 or F2 | L2 is an ignition lockout. F2 is flame loss | Too many resets bring up LC on current Logic models, or L5 on some older ones |
| Ideal | LC (L5 on some older models) | The boiler has been reset too many times in a short period: 5 resets in 15 minutes on Logic models | Stop resetting and check your manual |
| Baxi | E133 | Baxi links it to the gas supply, the ignition or flame, or a blocked condensate pipe | No number. Baxi says frequent lockout indicates a fault |
One older Ideal Logic manual words L5 as “too many resets on room stat”, so check the manual for your own model. The full code lists sit on our Worcester boiler error codes, Vaillant boiler error codes, Ideal boiler fault codes and Baxi boiler error codes guides. A Worcester showing EA with no number after it is covered in our Worcester EA error code guide.
What causes boiler ignition lockout?
Rule out the condensate pipe and the gas supply first, because those two you can check yourself. Everything after them is an engineer job.
Has the condensate pipe frozen or blocked?
In winter it’s the first thing to look at. A condensing boiler drains waste water through a plastic condensate pipe, and the section outside can freeze in a hard frost. Water backs up and the boiler shuts down. Worcester links EA 229 to a blocked condensate trap, and Baxi links E133 to a blocked condensate pipe.
Boilers on the exposed Pennine hillsides around Queensbury and Thornton tend to be the first to go when a cold snap sets in. Our boiler condensate pipe guide explains how the pipe works, and you can defrost your condensate pipe yourself with warm water.
Is gas reaching the boiler?
No gas, no flame. A prepayment meter that’s run out of credit, a gas valve that’s been turned off or low gas pressure can all cause a lockout. You can check the first two. Low gas pressure needs a Gas Safe registered engineer to test it.
Is the ignition electrode or flame sensor worn?
The electrode makes the spark and the flame sensor confirms the flame. Both wear or get dirty over the years, and if either one can’t do its job, the boiler assumes it hasn’t lit. It’s one of the cheaper lockout repairs. It’s still an engineer job.
Could the gas valve be faulty?
If the gas valve doesn’t open properly, gas never reaches the burner. Gas valves cost more to replace, and on an older boiler this is often the repair that tips the sums towards a new one.
Is the flue blocked, or is wind blowing into it?
A blocked flue, or strong wind blowing straight into it, can stop the flame lighting or staying lit. Leave the flue alone. If the lockouts only happen on windy days, tell the engineer, because it narrows the search down quickly.
Has the PCB failed?
The printed circuit board runs the ignition sequence. When it fails, the boiler can lock out even with a good gas supply and healthy parts. Our guide to boiler PCB faults covers the other signs to look for.
What can I safely check when my boiler is in lockout?
Work through these in order. None of them need the casing off.
- Do your other gas appliances work? If the hob won’t light either, the problem is the gas supply, not the boiler.
- Has the meter run out of credit? A prepayment meter cuts the gas when it does.
- Has the gas isolation valve been turned off? It’s usually a yellow-handled valve on the gas pipe to the boiler, and Ideal lists it as one of its own checks.
- Is the condensate pipe frozen? In frosty weather, look at the outside section for ice and thaw it with warm water, never boiling.
- Reset once. Follow the steps in your boiler’s manual. If it fires and keeps running, the cause was probably a one-off.
Never take the casing off yourself. Anything behind the front panel is a job for a Gas Safe registered engineer.
How many times should you reset a boiler in lockout?
Go by your manufacturer, not a number you’ve read on a forum. The brands don’t agree:
- Vaillant’s manual says reset up to 3 times, then call a competent person.
- Ideal stops you itself on some models, showing LC (L5 on some older models) once you’ve reset too often.
- Baxi and Worcester Bosch don’t give a number at all. Baxi’s line is that frequent lockout indicates a fault.
Whatever the brand, if it locks out again straight after a reset, stop there. Pressing the button again won’t fix a worn electrode or a gas valve that’s on its way out. It just delays the visit from a Gas Safe registered engineer.
Is boiler ignition lockout dangerous?
The lockout itself isn’t. The boiler has cut the gas because it couldn’t prove a flame, which is exactly what you want it to do. The risk comes from working around it, by resetting it again and again or taking the casing off for a look. If you smell gas at any point, leave the boiler alone and call 0800 111 999.
What does an ignition lockout repair cost?
These are typical UK prices for the parts most often behind a lockout:
| Repair | Typical UK cost |
|---|---|
| Call-out and diagnosis | £80 to £150 |
| Ignition electrode or flame sensor | £150 to £300 |
| Gas valve | £180 to £220 (Checkatrade, 2023) up to £250 to £450 (Heatable) |
| PCB | £300 to £600+ |
An electrode or sensor is a fair repair on a younger boiler. Gas valves and PCBs are where the bills start to climb.
Should I repair it or replace the boiler?
Repair it if the boiler is young and the lockout was a one-off. Which? recommends repairing where you can, and on a newer boiler we’d say the same. Age and repeat faults change the picture. On a boiler of 8 years or more, repeat lockouts usually come back to the gas valve, the electrodes or the PCB, which are the expensive parts, and fixing one rarely stops the next.
At that point the money is better put towards a boiler replacement, with long, market-leading warranties available through Clever Energy. You can spread the cost with boiler finance, and our guides on when a boiler needs replacing and how much a new boiler costs help with the sums.
Lockout codes on Worcester, Ideal, Vaillant and Baxi boilers
Worcester Bosch
A Worcester that can’t prove a flame after ignition shows EA 227, and one that loses its flame mid-run shows EA 229. If it won’t power up at all, our guide to a Worcester boiler not turning on is the better fit. As accredited installers, we fit the current range through our Worcester Bosch boiler installation service.
Ideal
Ideal uses L2 for an ignition lockout and F2 for flame loss. Our Ideal boiler fault codes guide explains how the codes differ between ranges, and our Ideal boiler installation page covers the newer models.
Vaillant
Vaillant ecoTEC boilers show F.28 when there’s no flame during ignition and F.29 when the flame goes out. A Vaillant that has stopped with nothing on the display is covered in Vaillant boiler not working with no fault code, and Vaillant boiler installation is the place to look if yours is getting on.
Baxi
Baxi’s lockout code is E133, and our Baxi E133 guide covers it in full. The Baxi boiler installation page has the current models.
Boiler ignition lockout FAQs
How many times can I reset a boiler in lockout?
It depends on the brand. Vaillant says 3 times, some Ideal models block further resets with LC or L5, and Baxi and Worcester give no number, so reset once and get a Gas Safe registered engineer if it locks out again.
Why does my boiler lock out in cold weather?
Usually a frozen condensate pipe. Thaw it with warm water and reset once, following our guide to defrosting a condensate pipe.
Is a boiler lockout dangerous?
No. It’s a safety feature that cuts the gas when no flame is detected. Don’t keep resetting it, and call 0800 111 999 if you smell gas.
Why does my boiler lock out after a few minutes?
It’s usually losing the flame while it runs. Worcester shows this as EA 229 and Vaillant as F.29, and a blocked condensate trap, a gas supply problem or a dirty flame sensor are the likely causes. If it switches off with no code at all, read why your boiler keeps turning off.
Can I fix ignition lockout myself?
Only the simple checks: other gas appliances, meter credit, the isolation valve, the condensate pipe and one reset. Electrodes, sensors, gas valves and PCBs all need a Gas Safe registered engineer, and our 10 most common boiler problems guide covers the other faults worth knowing about.
Get a new boiler with Clever Energy
We fit new boilers in Bingley, Bradford, Leeds, Keighley, Huddersfield, Halifax and across Yorkshire, the North West and the Midlands, from Manchester and Liverpool down to Birmingham and Leicester. Start with our boiler installation page, or go straight to Worcester Bosch, Vaillant, Ideal or Baxi installation. Get your fixed online boiler quote in a few minutes, or request a callback if you’d rather talk it through. Once it’s fitted, a Clever Care plan keeps your new boiler protected.