Worcester Bosch boiler fault codes
Worcester Bosch publish their fault codes to the trade, not to owners. There is no householder code table on their website; the codes live in the installation and servicing instructions written for each range, and that is where these pages are read from. It also explains the confusion around Worcester codes: the same fault is written three different ways depending on how old the boiler is — four, counting the boilers from before the Greenstar name, which have no display at all and flash their indicator lights instead. A Greenstar i or Compact shows a letter pair such as EA with a three-digit number such as 227 beneath it, and both halves matter. A CDi Classic shows only the letters. A Greenstar 8000 Life shows only the number. Quoting half a code is why so many Worcester diagnoses go round in circles — EA 227 and EA 229 are different faults with different fixes.
Where the code shows on a Worcester Bosch
Work out which display you have before you look anything up, because it decides what the characters mean. Five generations are in UK homes. The Greenstar CDi Classic and its Heatronic 3 relatives — the earlier CDi combi, system and regular boilers, the Highflow CDi and the FS CDi — have a small display that normally shows the flow temperature and, in a fault, two characters only: EA, E9, A1, b1, Fd. There is no number. The Greenstar i and i System from 2015, and the CDi Compact, Si Compact and 27i/30i System Compact from 2014, show the two characters with a three-digit cause code beneath them, and Worcester's user guide asks you to quote both, their example being "EA and 227". During a lockout the number flashes on the display; during a blocking pause it is only visible in the info menu. The Greenstar 8000 Life, 8000 Style and 8000+, the 4000 and the 2000 have a text display and give a plain number — 224, 227, 1017, 2951 — alongside a description, with no letters at all. Worcester sort those numbers into categories: operating messages in the 200s that are not faults, blocking faults the boiler clears itself, locking faults that need the keys, and maintenance codes in the 1000s that leave it running. On the 2000 a fault shows with an H symbol, and on the 8000 Life the display alternates LoPr with the reading when the pressure has dropped out. And the Greenstar 24i and 28i Junior, the 25Si and 30Si, the Ri and the Ri Compact have no display. On those the blue light is the code, and Worcester do publish its meaning, in the installation instructions rather than the user guide: a slow flash that is mostly off with the reset button flashing is an ignition lockout; a slow flash that is mostly on is a flue or heat exchanger overheat; a fast flash with the reset button dark is a sensor, fan or code plug fault; a fast flash with the reset button flashing is an internal fault; and two or five pulses mean an engineer has left the boiler in its minimum or maximum service mode. The 27Ri and 30Ri Compact from 2015 are the exception even here: their light counts one to five flashes after a five-second gap, in three groups told apart by where a burst of four fast flashes falls, and the fifteen meanings are on the blue light page. A steady blue light is a boiler switched on and healthy. Count the pattern before you ring anyone. Older still are the Worcesters from before the Greenstar name — the 24CDi, 28CDi and 35CDi II, the 26CDi Xtra, the 25Si and 28Si, the 24i and 28i Junior, the Si II, the CBi and the floor-standing Highflow 400 Electronic — which have indicator lights, mostly red, and no display: a light flashing slowly is a lockout you may reset once, a light flashing fast is a fault the boiler waits out or an engineer clears, and the red light page gives the decode Worcester print in each user guide. The 2004 to 2007 Greenstar HE range, the R 25 and 30 HE combi, R 28 HE system and 30, 35 and 40 HE Plus, is the odd one out: it has the two-character display of the CDi Classic and shares its table. Two things these pages do not cover. Worcester's oil-fired boilers — the Greenstar Heatslave II combi, whose display uses the same letter-pair-and-number system and adds burner codes such as 9F 855, and the Danesmoor, Camray and earlier Heatslave, which have a lockout light rather than codes — are serviced by OFTEC registered technicians rather than Gas Safe engineers, and oil work is not restricted by law the way gas work is. The Heatslave II's own codes are written up here with that trade named on each page: 9F 855, the burner lock-out, and 9F 856 after four resets; E9 210, the flue gas, air pressure and tank thermostat trip; A0 809, the thermal store sensor; E2 233 and 9A 360, the code plug; and H27 and H29, the two advisories. The codes it shares with the gas Greenstar i — E5 218, E9 219, E2 222 and the F0 electronics numbers — mean the same thing on the Heatslave, but those pages are written for gas boilers and name a Gas Safe engineer; for the Heatslave the person to call is an OFTEC registered technician. The Danesmoor, Camray and earlier Heatslave have no codes to write up. Nor are the letterless status numbers an engineer reads in the info menu.
How to reset a Worcester Bosch
Worcester publish a different reset for each generation, and they are not interchangeable. Greenstar CDi Classic and the other two-character displays: press the reset button for three seconds; the button and the blue fault indicator stop flashing when it has taken. The same user guide says five seconds after thawing a frozen condensate pipe, so anything from three to five is what Worcester mean. Greenstar i, i System, CDi Compact, Si Compact and i System Compact: there is a dedicated reset button, and you press it briefly once — the word Reset and a tick appear, and if it worked the boiler returns to normal. Do not press the blue light; on the Greenstar i it is an indicator, not a button. Greenstar 8000 Life, 8000 Style, 8000+, 4000 and 2000: there is no reset button. Press the up and down arrow keys together — the 8000 Life user guide says until the fault disappears, the 8000+ and 4000 guides until Reset is displayed, the 2000 manual until the H and warning symbols disappear, or switch its power off and on — and the boiler restarts and shows the current flow temperature. On the 8000+, 4000 and 2000 there is a limit: five locking-fault resets inside fifteen minutes puts the boiler into the 2980 super lock-out, which only an engineer can clear. Greenstar 24i/28i Junior and 25Si/30Si without a display: press the reset button for approximately five seconds, until it stops being lit. Greenstar Ri and Ri Compact: there is no button at all — turn the central heating temperature knob fully anticlockwise to its RESET position, hold it there for about five seconds, then turn it back to where it was. Two things on these boilers wipe settings rather than clear faults, and both are engineer procedures worth knowing about so you do not stumble into them. On a Greenstar i, holding the spanner and OK keys for about eight seconds opens the appliance menu, from which a further press returns every boiler setting and weather sensor setting to factory defaults. On an 8000 Life, service function 4-F1 in the engineer menu — reached by holding the heating and hot water keys together — resets the appliance to its basic settings and discards the installer's commissioning values. On the i Junior, holding the service and eco buttons for about seven seconds until every button flashes resets the control board itself. The pre-Greenstar boilers have their own: on the 24CDi, 28CDi, 35CDi II, 26CDi Xtra, 25Si and 28Si, and on the 24i and 28i Junior and Si II, press the reset button — on the Junior it is the fault light itself — for five seconds if a light is flashing slowly, and switch the power off and on at the socket if it is flashing fast; on the CBi and the Highflow 400 Electronic there is no button, and the heating temperature knob turned fully anticlockwise and back is the reset; on the 24i and 28i RSF a lockout is cleared by ending the demand. The Greenstar HE of 2004 to 2007 is held until the display shows two dashes. Whatever the range, Worcester say some codes cannot be cleared by a simple reset because of the internal safety systems, and their instruction is then to call them rather than keep trying. Stop after two attempts on any ignition code, stop immediately on any smell of gas or fumes, and for anything involving the gas valve, the flue or combustion the fix is a Gas Safe registered engineer's, not yours.
Most common Worcester Bosch faults
The Worcester Bosch codes people look up most.
- EA 227Stop — call an engineerThe boiler tried to light and never detected a flame, so it has shut the gas off and locked out. This is the most common Worcester fault code.
- CE 207Get it checkedSystem water pressure has dropped too low for the boiler to run safely. Topping the system back up to 1.2 bar usually clears it in five minutes.
- E9 219Stop — call an engineerThe boiler has overheated and the safety thermostat has tripped. Water is not carrying heat away from the exchanger, and it should not be run until that is fixed.
- C6 224Get it checkedThe fan is not reaching the speed the boiler asked for, so combustion cannot be confirmed as safe and the burner has been prevented from firing.
Every Worcester Bosch fault code
54 published codes. Filtering happens in the page — every one is in the HTML.
Showing 54 of 54 codes
Worcester Bosch models
Codes can differ between generations. Check yours.
- 24CDi, 28CDi, 35CDi II, 26CDi Xtra, 25Si/28Si, 24i/28i Junior, Si II, CBi and Highflow 400
- Greenstar 2000 and Worcester 2000
- Greenstar 24i/28i Junior, 25Si/30Si Mk4 and Ri
- Greenstar 4000
- Greenstar 8000 Life, 8000 Style and 8000+2019+
- Greenstar CDi Classic2010–2019
- Greenstar CDi Compact, Si Compact and i System Compact2014+
- Greenstar HE (2004–2007)2004–2007
- Greenstar Heatslave II (oil)
- Greenstar i and i System2015+
Guides that help with Worcester Bosch faults
Boiler fault codes explained: what they actually tell you
Codes look like diagnoses and are not. Understanding which family a code belongs to turns a meaningless number into a genuinely useful starting point.Read the guideHow to repressurise a boiler
The five-minute job that resolves more no-heating calls than any other. Here is how to do it properly, and how to tell when topping up is the wrong answer.Read the guideWhat a Gas Safe engineer actually checks in a boiler service
Most people pay for this once a year and stand in another room while it happens. Here is what should be going on, which test cannot be faked, and how to tell a real service from twenty minutes and an invoice.Read the guideWhat to do when your condensate pipe freezes
The single most common winter boiler fault, and one of the few you can genuinely fix yourself in fifteen minutes with a kettle and some patience.Read the guide
Looking for Worcester Bosch’s own support? www.worcester-bosch.co.uk. We are not affiliated with Worcester Bosch.