Fault guide
Worcester Bosch EA fault code, what it means and what causes it
EA is one of the most common Worcester Greenstar lockouts. It means the boiler tried to light and never saw a flame, so it stopped rather than kept pumping gas into the combustion chamber.
What the boiler is telling you
On Worcester Greenstar boilers, EA is a flame loss or flame detection failure. The ignition sequence ran, the gas valve opened, and the ionisation probe did not confirm a flame within the allowed window. The boiler then locked out as a safety measure.
That is the boiler doing its job. The question is why the flame did not establish, and there are only a handful of realistic answers.
The usual causes, in the order we check them
EA has a short list of realistic causes, and we work through them in this order.
- Gas supply: an emergency control valve turned off, a spent prepayment meter, or low gas pressure at the appliance.
- Condensate blockage: a frozen or blocked condensate pipe backs up and prevents the boiler running. Very common after a frost.
- Ignition electrodes: worn, sooted or wrongly gapped electrodes fail to strike a reliable spark.
- Flame sensing and earthing: a poor earth or a degraded ionisation probe means the flame is there but the boiler cannot see it.
- Gas valve: less common, but a valve that is not opening correctly will produce EA every time.
What you can safely check first
A few checks are safe for anyone to make before calling an engineer.
- Is the gas on elsewhere in the house, at the hob for example?
- Is there credit on the meter?
- Is the white condensate pipe outside frozen or blocked? Thaw it with warm, never boiling, water.
- Press reset once and watch what happens.
- Anything beyond that is Gas Safe work: do not remove the boiler casing.
What we do on site
We test working gas pressure and gas rate at the meter, inspect and set the electrodes, check the condensate route end to end, measure the ionisation current, and analyse combustion with a calibrated analyser. That sequence tells us which of the causes above is the real one, rather than replacing parts and hoping.
Most EA lockouts we attend in Warwickshire are resolved on the first visit, because the common causes are things we carry parts for.
Questions we get asked
- What does EA mean on a Worcester Bosch boiler?
- EA is a flame detection lockout. The boiler asked for gas, attempted ignition and did not sense a flame, so it shut itself down and locked out on purpose.
- Can I reset an EA fault myself?
- Reset once. If the boiler fires and stays running, keep an eye on it. If EA returns, stop resetting and get it looked at, because repeated ignition attempts on an unresolved fault are not doing the boiler any good.
- What usually causes an EA lockout?
- Most often a gas supply issue, dirty or worn ignition electrodes, a blocked condensate pipe backing up into the boiler, an earthing or flame sensing fault, or a failing gas valve.