Worcester Bosch EA 227 Fault Code: Causes, Fixes & Repair Costs
What does the Worcester Bosch EA 227 fault code mean?
The EA 227 fault code means your Worcester Bosch boiler attempted to light the burner, failed to detect a flame through ionisation, and has locked itself out as a safety precaution. The boiler typically makes several ignition attempts — sparking and waiting to sense a flame signal — and when no ionisation is confirmed after repeated tries, it shuts down completely and displays EA 227. This lockout is deliberate: it stops unburnt gas from accumulating inside your home. The code appears across the Greenstar range including the Greenstar i, Greenstar Si, and Greenstar CDi (combi, system, and regular variants). Note that Worcester Bosch fault codes often appear with a numeric sub-code after the letters — EA 227 is the most common EA lockout, but you may also see EA 229 (flame loss during operation rather than at start-up) or EA 217 (ignition electrode circuit fault). All three point to the ignition and flame-detection circuit and are covered by the guidance on this page.
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
- Gas supply interrupted or isolation valve closed Common
If the gas supply to the boiler is off — whether because the isolation valve on the supply pipe is turned across the pipe, a prepayment meter has run out, or there is a wider mains interruption — there is nothing to ignite. This is the first thing to rule out because it costs nothing to check and resolves a surprising proportion of EA 227 calls.
- Faulty or dirty ignition and flame-sensing electrodes Common
Two electrodes sit inside the combustion chamber: one creates the spark to ignite the gas, and a separate sensing electrode confirms via a small electrical signal (ionisation) that a flame is actually present. Carbon deposits, cracking, or misalignment of either electrode means the boiler sparks but receives no confirmation signal, triggering the EA 227 lockout. Electrode faults are the single most common engineering diagnosis for this code.
- Frozen or blocked condensate pipe Common
In cold weather, the white plastic condensate pipe that runs outside to a drain can freeze solid. When this pipe is blocked, the boiler cannot expel waste water from the condensing process and will lock out. This is a seasonal cause that spikes in winter and is one of the few EA 227 triggers a homeowner can safely resolve themselves.
- Low or insufficient gas pressure at the boiler Sometimes
Even with the supply on, gas pressure at the boiler may be too low for reliable ignition. This can stem from issues with the meter regulator, undersized pipework, or a problem elsewhere on the supply. The boiler will attempt to fire but the burner won't sustain a flame, causing repeated ignition failures and an EA lockout.
- Faulty gas valve Sometimes
The gas valve controls how much gas enters the burner. If it sticks, fails to open fully, or cannot modulate correctly, gas delivery to the burner is unreliable. This fault often develops gradually — the boiler starts locking out intermittently before failing consistently. Only a Gas Safe engineer can test and replace the gas valve.
- Blocked burner or pilot jet Sometimes
Small particles of carbon, dust, or debris can partially or fully block the burner jet, preventing enough gas from reaching the ignition point. Even a minor restriction is enough to cause failed ignition and an EA 227 lockout.
- Flue obstruction Rare
A partially or fully blocked flue prevents safe removal of combustion gases. This can disrupt the combustion process itself and, in some boiler configurations, contribute to ignition failure or flame instability that triggers the lockout.
- PCB fault or moisture damage Rare
The printed circuit board coordinates the ignition sequence. Internal water leaks, condensation, or component failure on the PCB can disrupt the signals sent to the ignition electrodes or the flame-sensing circuit, producing an EA 227 code even when the gas-side components are working. PCB faults are typically a diagnosis of exclusion.
How to fix it
- Check that gas is reaching other appliances in your home DIY safe
Turn on a gas hob ring or check another gas appliance. If nothing gas-powered is working, the problem is upstream of your boiler — contact your gas supplier. If you have a prepayment meter, check it has sufficient credit. Confirm the gas isolation valve on the pipe leading to your boiler is fully open (the handle runs parallel with the pipe, not across it).
- Inspect the condensate pipe for freezing (cold weather only) DIY safe
Locate the white plastic pipe, usually 21–32 mm diameter, exiting through an outside wall and running to a drain. If the weather is at or below freezing and the pipe feels solid, pour warm (not boiling) water along its length to thaw it. Once cleared, reset the boiler. If it fires successfully, consider insulating the pipe or fitting a frost protection kit to prevent a recurrence.
- Reset the boiler once or twice DIY safe
Press and hold the reset button (usually marked with a flame symbol or the word 'Reset') for around three seconds until the boiler attempts to restart. If it fires and runs normally, monitor it over the next day or two. If it locks out again quickly, repeated resets will not fix the underlying fault and can cause additional wear — proceed to calling an engineer.
- Do not attempt to inspect or adjust any gas components Gas Safe engineer
Gas valves, burner jets, ignition electrodes, ignition leads, and the gas supply pipework inside the boiler must only be touched by a Gas Safe registered engineer. Attempting DIY work on these components is illegal, dangerous, and will void your Worcester Bosch warranty.
- Contact a Gas Safe registered engineer to diagnose and repair the fault Gas Safe engineer
An engineer will carry out a systematic check: testing gas pressure at the boiler, inspecting and cleaning or replacing the ignition and flame-sensing electrodes, examining the ignition leads, testing the gas valve operation, checking the flue for obstructions, and assessing the PCB for damage. Always ask to see the engineer's Gas Safe ID card before work begins — you can verify registration at gassaferegister.co.uk.
Parts you may need
- Ignition electrode · from £35
- Flame-sensing electrode · from £30
- Ignition lead set · from £45
- Gas valve (Greenstar range) · from £180
- Condensate pipe frost protection kit · from £20
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 £120–£380, depending on the underlying cause.
Frequently asked questions
Can I reset my Worcester Bosch EA 227 fault myself?
Yes, a single reset is safe and worth trying — sometimes a one-off glitch causes the lockout and the boiler fires normally afterwards. Press and hold the reset button for around three seconds. If the boiler locks out again within a short period, do not keep resetting it. Repeated resets on a genuine fault cause extra wear on the ignition components and PCB, potentially turning a straightforward repair into a more expensive one. Two resets without success means you need an engineer.
What is the difference between EA 227, EA 229, and EA 217?
All three are EA-series lockout codes related to ignition and flame detection, but they point to slightly different stages of the process. EA 227 means the boiler failed to detect a flame at start-up after multiple ignition attempts. EA 229 indicates the flame was established but then lost during normal operation — suggesting a gas supply fluctuation or a flame-sensing fault rather than a pure ignition problem. EA 217 points more specifically to a fault in the ignition electrode circuit itself, such as a wiring or electrode failure. In practice, all three require a Gas Safe engineer to diagnose, and the physical components involved — electrodes, leads, gas valve — overlap significantly.
How much does it cost to fix EA 227 on a Worcester Bosch boiler?
For the most common cause — ignition or flame-sensing electrode replacement — you should budget roughly £120–£250 including parts and labour. A gas valve replacement typically runs £250–£380 for parts and labour combined. PCB replacement is less common as a root cause but can cost £400–£600 or more, which is worth weighing against the boiler's age. If your boiler is over ten years old and the engineer finds both a failing gas valve and PCB damage, it may be more economical to replace the boiler entirely rather than invest heavily in repairs.
Will a frozen condensate pipe cause EA 227?
Yes. During cold snaps, a frozen condensate pipe is one of the most common triggers for boiler lockouts across all fault codes — including EA 227. The good news is that this is one of the few causes you can fix yourself: thaw the external pipe with warm water and reset the boiler. If it fires up immediately, you have your answer. To prevent it happening again, insulate the exposed section of pipe with foam lagging or ask an engineer to fit a frost thermostat and trace heater kit.