Worcester Bosch EA 229 Fault Code: Causes, Fixes & Repair Costs
What does the Worcester Bosch EA 229 fault code mean?
The EA 229 fault code means your Worcester Bosch boiler established a flame successfully but then lost it while running. This is a flame-loss-during-operation fault, not a failure to ignite in the first place — that distinction matters because the boiler proved it could light, but something caused the flame to extinguish unexpectedly mid-cycle. As a safety precaution, the boiler locks out immediately to prevent unburnt gas from building up. It will not fire again until the underlying cause is resolved and the boiler is reset. The EA family of fault codes on Worcester Bosch boilers covers ignition and flame-related errors; EA 229 specifically points to flame loss during a run cycle, whereas related sub-codes such as EA 227 indicate a failure to establish a flame at all, and EA 338 relates to multiple failed ignition attempts. If your display shows EA 229, the burner did light — the problem lies in what caused it to cut out.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Frozen or blocked condensate pipe Common
During cold weather the small plastic condensate pipe — which runs from the boiler through an external wall — can freeze solid, blocking drainage. When condensate backs up, it can disrupt combustion and trigger a lockout. A blocked internal condensate trap caused by sludge or debris produces the same effect even in mild weather.
- Faulty or drifted gas valve Common
The gas valve meters fuel delivery to the burner. If it is sticking, not opening fully, or has drifted out of calibration over years of use, the flame may ignite correctly but quickly weaken and die. This is particularly common on boilers that have missed annual services, allowing the valve to deteriorate without correction.
- Low mains gas pressure Sometimes
If the gas pressure arriving at the boiler is below the required level — due to a supply issue, a frozen outdoor meter regulator in winter, or a problem with the meter itself — the resulting weak flame cannot sustain itself and the boiler trips out on flame loss.
- Blocked or restricted flue Sometimes
A partial blockage in the flue, whether from a bird nest, debris, or a damaged terminal, upsets the combustion air-to-gas ratio. This starves the burner of oxygen, causing the flame to become unstable and eventually extinguish during a firing cycle.
- PCB flame-detection fault Sometimes
The printed circuit board monitors the ionisation signal from the flame sensor to confirm combustion is sustained. If the PCB or its connections develop a fault, it may incorrectly report that the flame has gone out even when it has not, triggering a spurious lockout. This fault is often intermittent and difficult to reproduce consistently.
- Heat exchanger fouling Rare
On older Worcester Bosch boilers, accumulated scale, sludge, or combustion deposits on the heat exchanger can restrict heat transfer and interfere with burner performance to the point where flame stability is compromised. This tends to develop gradually and is picked up during routine servicing.
How to fix it
- Check that your gas supply is working DIY safe
Before doing anything else, confirm that other gas appliances in the property — a gas hob or gas fire, for example — are working normally. If nothing gas-powered will light, the issue is with your supply rather than your boiler. Contact your gas supplier or call the National Gas Emergency Service on 0800 111 999 if you suspect a supply failure or smell gas.
- Inspect and thaw the condensate pipe if the weather is cold DIY safe
Locate the white plastic condensate pipe where it exits through an external wall — it is typically 21.5 mm in diameter and leads to an outside drain or soakaway. If temperatures have been at or below freezing, this pipe is the most likely culprit. Pour warm (not boiling) water over the frozen section, or wrap it with a warm cloth or hot water bottle. Avoid using anything that could crack the pipe. Once water is flowing freely, proceed to reset the boiler. Insulating the pipe afterwards will help prevent a repeat.
- Reset the boiler once DIY safe
Press and hold the reset button on your Worcester Bosch boiler for approximately three seconds. One reset attempt is sufficient. If the EA 229 code returns after a single reset, do not keep pressing reset — doing so can mask an underlying fault and may not be safe if there is a genuine combustion issue.
- Check the boiler system pressure DIY safe
Look at the pressure gauge on the boiler. Worcester Bosch boilers typically require a cold-fill pressure of around 1.0–1.5 bar. If the needle has dropped below 0.5 bar, top up via the filling loop following your boiler manual instructions. Low pressure alone does not cause EA 229, but it can contribute to unstable operation — and it is worth ruling out while you have the boiler in front of you.
- Call a Gas Safe registered engineer to diagnose and repair the fault Gas Safe engineer
If the fault persists after the steps above, the cause requires professional investigation. A Gas Safe registered engineer will check gas valve operation and calibration, inspect and clean the condensate trap, test flue integrity, assess burner and heat exchanger condition, and evaluate the PCB flame-detection circuit. Gas valve adjustment or replacement, PCB repair, flue unblocking, and any internal component work are all legally required to be carried out by a Gas Safe registered engineer — not a homeowner.
Parts you may need
- Gas valve (Worcester Bosch compatible) · from £180
- Condensate trap / sump assembly · from £25
- Flame sensor / ionisation probe · from £20
- PCB (main printed circuit board) · from £280
- Condensate pipe insulation lagging · from £8
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £80–£350, depending on the underlying cause.
Frequently asked questions
Can I keep resetting the boiler to get it running again?
You can try one reset after checking the condensate pipe and gas supply, but repeatedly pressing reset without fixing the root cause is not advisable. Each time the boiler fires without a stable flame, unburnt gas could accumulate, and you risk damaging internal components. If the fault returns after a single reset, stop and call a Gas Safe engineer.
How do I know if it is just the condensate pipe and not something more serious?
A frozen condensate pipe is by far the most common cause of EA 229 during cold weather. If temperatures have been at or below freezing, you can hear or see ice on the external pipe, or the fault appeared overnight in winter, start there. If the weather has been mild, or if thawing the pipe and resetting does not clear the fault, the cause is almost certainly internal — a gas valve, flue, or PCB issue — and you will need an engineer.
How much does it cost to fix EA 229?
Most EA 229 repairs fall in the range of £80–£350. A call-out and diagnosis typically costs £80–£120, and if the gas valve simply needs recalibration, that is often included in the call-out fee. A full gas valve replacement on a Worcester Bosch boiler is around £300 including labour. If the PCB has failed, costs can rise to £450–£600 or more including parts and diagnostics — at that level it is worth considering the age of the boiler, as a replacement installation may be more cost-effective on a boiler over 10 years old.
Will an annual service prevent EA 229 from coming back?
Regular annual servicing significantly reduces the risk. During a service a Gas Safe engineer cleans the burner, condensate trap, and heat exchanger, checks gas valve calibration, and tests all safety devices. These are precisely the components involved in most EA 229 faults. Insulating the external condensate pipe will also prevent freeze-related lockouts in winter.