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Worcester Bosch EA 229 fault codewhat it means and how to fix it

Get it checkedBoilerGreenstar i and i System ErP and the CDi Compact, Si Compact and 27i/30i System Compact, where EA is shown with 229 beneath it and Worcester define it as loss of ionisation signal during operation; the Compact tables add EA 230, ionisation signal out of bounds. On the CDi Classic the display shows EA alone for any flame fault, so a flame lost mid-run and one never established look identical. Greenstar 8000 Life, 8000 Style, 8000+, 4000 and 2000 show 229 alone as a blocking fault, flame failed during burner operation, which the boiler retries itself; repeated losses become the 2951 lockout. The Greenstar 4000 and 2000 also publish 2927 for a flame failing during operation, and the 2000 logs 1014 for an ionisation current too low.Last updated

The burner lit and then the flame was lost during operation. That is a different fault from failing to light in the first place.

Take care

Some of this is safe to check yourself, but the repair itself is not. If the fault comes back after one reset, stop resetting it and get a Gas Safe registered engineer to look at the Worcester Bosch properly.

What EA 229 means

EA 229 is worth separating carefully from EA 227, because the two get treated as the same thing and they are not. EA 227 means no ionisation was detected after ignition — the burner never established a flame. EA 229 means an established flame was subsequently extinguished, or that ionisation was lost during the burning phase. So on an EA 229 the electrode sparked properly, gas arrived, the valve opened and combustion started.

Something then interrupted it. That rules out a good deal and points at a shorter list: a gas supply that sags under load rather than being absent, condensate backing up once the appliance starts producing it, or disturbance at the flue. Worcester's own literature mentions a blocked sump and strong wind into the flue as causes, and both are worth taking seriously. Wind in particular is under-appreciated — an exposed terminal on a gable end can genuinely blow a flame out, and the fault will track the weather rather than the clock.

What causes it

Causes of the Worcester Bosch EA 229 fault code, most common first
CauseWhat is actually happeningHow likely
Condensate sump or trap blockedWorcester name a blocked sump directly. Condensate backs up into the combustion chamber shortly after firing, which is why the appliance runs for a consistent short period each time before dropping out.Common
Gas supply inadequate under full rateEnough to light, not enough to sustain. Typically worse when a hob or another gas appliance is running simultaneously.Common
Wind into the flue terminalNamed in Worcester's documentation. An exposed terminal on a gable or in a wind funnel between buildings can disturb combustion enough to lose the flame. Suspect it if the fault follows the weather.Occasional
Flame sensing electrode losing signal when hotA marginal electrode reads adequately from cold and falls below threshold as the chamber heats and components expand.Occasional

What to try yourself

  1. Time it over two or three attempts. Note how long the appliance runs before the code appears. A consistent interval points at condensate; an erratic one points at gas supply or wind.

  2. Check whether it fails sooner with a gas hob running at full rate. If so, the supply is the likely constraint and needs an engineer with a manometer.

  3. Note whether it is noticeably worse on windy days. Only you can observe that over time and it is genuinely valuable to whoever attends.

  4. In cold weather, check the external condensate pipe for ice and thaw it with hand-hot water if you find any.

    Never use boiling water or any form of heat gun on a condensate pipe. Cold plastic cracks readily.
  5. Reset no more than twice, and give the engineer your timing observations. It will very likely save a return visit.

Get a Gas Safe registered engineer to look at your Worcester Bosch EA 229

We do not pass enquiries to a repair firm, so there is no form here. Find a Gas Safe registered engineer through the Gas Safe Register, and ask to see their registration card when they arrive — it is the register, not the van, that tells you they are qualified.

What it costs to fix

Typical repair cost

£90–£450

Time on site

25 minutes

Clearing a blocked sump or condensate trap is £90 to £170. An electrode is £120 to £200 fitted. A flue modification for wind exposure is £180 to £400.

Typical UK prices including parts and labour, updated September 2026. Your quote may differ.

Parts you may need

We may earn a commission if you buy a part through one of these links. It does not change what you pay, and it does not affect which parts we list.

Worcester Bosch Greenstar electrode set

87161431020£22–£52Authorised Worcester parts distributor

Price checked 28 September 2026

Condensate trap and siphon

COND-TRAP£15–£38Plumbing merchant

Price checked 28 September 2026

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Written by

Andrew Pickett

Researcher and writer

Last updated

Technical review

Not reviewed by an engineer

No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.

What we check instead

Sources and how we verified this

We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.

  • Manufacturer technical and service documentation

This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.

Read our full verification process

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