Worcester Bosch EA Fault Code: Causes, Fixes & Repair Costs
What does the Worcester Bosch EA fault code mean?
The EA fault code on a Worcester Bosch boiler means the appliance has tried to light its burner — typically up to four attempts — but could not confirm a stable flame on any of those tries. Rather than continuing to attempt ignition (which would risk releasing unburnt gas), the boiler's PCB deliberately locks the unit out and displays EA to alert you. While locked out, both heating and hot water are unavailable. You may also notice a flashing blue light on the display. Some Worcester Greenstar models add a numeric suffix to give engineers a more precise starting point: EA 227 specifically indicates that the flame signal was lost partway through a firing cycle rather than failing to establish at all, suggesting the flame lit briefly but could not be sustained. Whichever sub-code appears, the underlying theme is the same — the boiler cannot confirm a flame is safely burning.
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 off Common
If the gas supply to the property is disrupted — due to a regional outage, a closed isolation valve on the supply pipe, or a prepayment meter that has run out of credit — the boiler simply has no fuel to ignite. Test another gas appliance such as your hob: if that also fails to light, the fault lies upstream of the boiler entirely rather than inside it.
- Faulty or worn ignition electrode / flame sensor Common
The ignition electrode creates the spark that lights the gas, while a separate flame-sensing electrode (or the same combined component) confirms the flame is present. Both can degrade over time through carbon build-up, corrosion, or physical misalignment. Even a slightly dirty or displaced electrode can prevent a reliable spark or cause the boiler to fail to recognise a flame that is actually present. This is one of the most frequent causes engineers find when attending an EA fault.
- Frozen or blocked condensate pipe Common
Condensing boilers expel acidic waste water through a plastic condensate pipe, which often routes externally. During cold snaps, the water inside can freeze and cause a back-up that triggers a lockout — sometimes logged as an EA code. Look for a white plastic pipe exiting the boiler to an outside wall or drain; visible frost or ice around it is a strong indicator.
- Faulty gas valve Sometimes
The gas valve meters the precise amount of gas entering the burner. If the valve sticks, fails to open fully, or its actuator coils develop a fault, insufficient gas reaches the burner and no stable flame can form. The boiler then locks out after exhausting its ignition attempts. This component requires a Gas Safe engineer to diagnose and replace.
- Restricted flue or blocked air intake Sometimes
The boiler needs a clear path to draw in fresh air and expel combustion gases through the flue. A bird's nest, debris, or ice at the flue terminal can restrict airflow enough to destabilise combustion or prevent ignition entirely, triggering the EA lockout. Check the outside flue terminal for obvious obstructions without climbing or working at height.
- Faulty fan Sometimes
Before ignition can begin, the boiler's fan must reach a set speed to prove the flue is clear and ventilation is safe. If the fan is failing — through worn bearings, a seized motor, or electrical fault — the boiler will not proceed to the ignition stage. A C6 code may appear alongside EA on some models when the fan is the root cause.
- PCB (printed circuit board) fault Rare
The PCB orchestrates every stage of the ignition sequence. On rare occasions the board itself develops a fault — through age, moisture ingress, or a component failure — that causes it to misread sensor signals or fail to trigger ignition correctly. PCB faults tend to produce other accompanying error codes and are usually only confirmed after all other components have been ruled out.
How to fix it
- Check that other gas appliances are working DIY safe
Turn on your gas hob or check another gas appliance in the property. If nothing gas-powered works, you likely have a supply issue unrelated to the boiler. Contact your gas supplier or check whether your prepayment meter needs topping up. Also confirm the gas isolation valve — usually a lever or handle on the gas pipe near the meter — is fully open (handle in line with the pipe).
- Look for a frozen condensate pipe DIY safe
During cold weather, locate the white plastic condensate pipe where it exits the boiler and runs to a drain. If you see ice or frost on or around it, thaw it by carefully pouring warm (not boiling) water along the pipe. Repeat until water flows freely, then proceed to reset the boiler. Consider lagging the pipe afterwards to prevent a repeat freeze.
- Reset the boiler once DIY safe
Once you have completed the checks above, attempt a single reset. On most Worcester Greenstar models this involves turning the main dial to the reset position and holding it for a few seconds, or pressing a clearly labelled reset button. The boiler will then run through its ignition sequence. If it fires up and runs normally, monitor it over the next hour. If the EA code returns, do not reset it again — further repeated resets can accelerate wear on ignition components and the PCB, potentially turning a straightforward repair into a more expensive one.
- If the fault persists, call a Gas Safe registered engineer Gas Safe engineer
A persistent EA fault — or one that clears on reset but keeps returning — needs professional diagnosis. A registered engineer will check gas supply pressure at the appliance, inspect and test the ignition electrode and flame sensor, examine the gas valve operation, and assess the fan and flue for any restrictions. They will also read any detailed sub-codes (such as EA 227) from the boiler's internal fault log to pinpoint the exact failure point. Do not attempt to open the boiler casing or interfere with gas components yourself.
Parts you may need
- Ignition / flame sensing electrode (or combined electrode assembly) · from £35
- Gas valve · from £180
- Boiler fan (flue fan assembly) · from £120
- PCB (printed circuit board) · from £220
- 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 £100–£350, depending on the underlying cause.
Frequently asked questions
What does EA 227 mean on a Worcester Bosch boiler?
EA 227 is a sub-code that appears on certain Worcester Greenstar models and gives engineers a more specific clue than the plain EA code alone. It indicates the flame was lost during operation — meaning the burner lit successfully but the flame then dropped out rather than failing to establish from the start. Common causes include a deteriorating flame sensor, a gas supply fluctuation, or intermittent issues with the gas valve. An engineer attending an EA 227 will typically focus on the sensing electrode and gas valve as the first ports of call.
Can I fix the EA fault myself, or do I need an engineer?
There are a few safe checks you can carry out yourself: confirming your gas supply is active, thawing a frozen condensate pipe in cold weather, and attempting a single boiler reset. However, if the fault persists after those steps, you will need a Gas Safe registered engineer. Anything involving internal components — the ignition electrode, gas valve, fan, or PCB — must only be handled by a qualified professional. Working on gas components without Gas Safe registration is illegal and dangerous.
How much does it cost to fix a Worcester Bosch EA fault in the UK?
Most people with an EA fault pay somewhere between £100 and £350 all-in, covering the engineer's call-out, diagnosis, and a standard parts replacement such as an ignition electrode or fan. A gas valve replacement typically adds up to around £300–£350 depending on the engineer's labour rate. PCB replacement is less common but can cost £350–£500 or more — if that figure comes up alongside a boiler that is already 12–15 years old, it is worth asking your engineer whether a new boiler would represent better value.
Why does my Worcester Bosch keep showing EA after I reset it?
A fault that clears on reset but keeps returning suggests the underlying cause has not gone away — the reset simply forces another ignition attempt, and the boiler locks out again when it faces the same problem. This pattern most commonly points to a worn ignition or flame-sensing electrode, an intermittent gas valve issue, or a recurring condensate freeze in cold spells. Resetting repeatedly is not a solution and risks adding wear to components. Book an engineer to investigate rather than continuing to reset.