Boiler
EA 338
The EA 338 error code on a Worcester Bosch boiler indicates a flame detection fault — the boiler is either failing to ignite or losing its flame shortly after lighting. This is a serious fault that will lock out your boiler and leave you without heating or hot water until it is resolved.
What does this error mean?
EA 338 means the boiler’s control board has detected that the burner flame is not being established or is cutting out unexpectedly during the firing sequence. Worcester Bosch boilers use an ionisation probe to confirm a stable flame; if that signal is absent or too weak, the boiler locks out as a safety measure. This is the boiler protecting your home from an unburned gas build-up — do not repeatedly attempt to restart it without investigating the cause.
Est. repair cost
£100–£300 total (callout + parts), depending on the failed component and engineer’s rates
🔍 Likely causes
🛠️ Step-by-step fix
Check your other gas appliances (hob, gas fire) are working. If nothing is working, call your gas supplier — there may be a supply interruption in your area. Do not attempt to restart the boiler.
Check your boiler’s gas isolation valve (the lever on the gas pipe leading into the boiler) is fully open — the handle should be parallel to the pipe.
Attempt a single manual reset by pressing and holding the reset button on the boiler’s fascia for 3–5 seconds. Wait 5 minutes to see if the boiler fires successfully.
If the boiler locks out again immediately or after one or two attempts, stop resetting it. Repeatedly forcing a restart when there is a genuine flame fault is unsafe.
Check the boiler is not in ‘Summer mode’ or that the programmer/thermostat is set correctly — rule out a controls issue before assuming a parts failure.
Beyond these steps, all further investigation and repair — including inspecting the ionisation probe, electrodes, gas valve, or PCB — must be carried out by a Gas Safe registered engineer. This is a legal requirement in the UK.
📞 When to call a professional
Call a Gas Safe registered engineer if the boiler locks out again after a single reset attempt, or if you smell gas at any point — in that case, do not reset the boiler, leave the property, and call the National Gas Emergency Service on 0800 111 999 immediately. When booking an engineer, tell them the exact error code (EA 338) and describe whether the boiler is failing to ignite at all or cutting out shortly after starting — this helps them bring the right parts.
⚖️ Repair or replace?
A Gas Safe engineer callout for an EA 338 fault typically costs £80–£180 depending on your region, with parts such as an ionisation probe (£15–£40) or ignition electrode (£20–£50) adding to the total. If your Worcester Bosch boiler is under 10 years old and has been regularly serviced, repair is almost always the right call. If it is over 12–15 years old and has a history of faults, a replacement A-rated boiler (typically £1,800–£3,000 installed) will be more cost-effective over the next five years.