The Worcester Bosch range of Combi, Regular and System oil boilers show either an error code on the digital display or have a sequence of flashing lights to help identify the cause of any faults.
Use the table below to find out what the various error codes and flashing light sequences on Worcester Bosch oil boilers all mean.
Lockout – false flame signal
| Fault Descriptione | System Behaviour |
| Red steady on | Lockout – no flame and safety time |
| Red 0.5 seconds on, red 0.5 seconds off | |
| Red 0.2 seconds on, red 0.2 seconds off | Lockout – maximum number of flame loss relights |
| Red 2.5 seconds on, orange 0.5 seconds on | Lockout – fan motor failure |
| Red 2.5 seconds on, green 0.5 seconds on | Lockout – oil valve circuit driver failure |
| Orange 0.5 seconds on, green 0.5 seconds on | Lockout – EEPROM failure |
| Red 0.5 seconds, on red ⅖ seconds off | Max pre-heat time exceeded |
| Green 0.5 seconds on, green 2.5 seconds off | Pre-heating time error |
| Green 0.5 seconds on, red 0.5 seconds on | Extraneous light – lockout after 25 seconds |
| Orange steady on | Pre-purge the burner remains in prep-purge After ignition burner remains in operation When anomalies disappear the burner re-starts |
| Orange 0.2 seconds on, green 0.2 seconds on | Control box internal error |
| Green 0.2 seconds on, green 0.2 seconds on | Remote reset button is activated for more than 60 seconds – when anomaly appears the burner does not stop |
| 1 | Control box is supplier with heat demand |
| 2 | The pre-heater is fitted or if no pre-heater is fitted is the link fitted |
| 3A | Green 0.5 seconds on / red 0.5 seconds on before lockout |
| 3B | Fan motor or oil pump is seized |
| 3C | 230 volts to motor across blue and black motor wired |
| 3D | Approximately 35 across blue and black motor wires |
| 4A | Motor gives 50 volts a.c across black and white wires |
| 5A | Burner fires when the photocell is covered |
| 5B | Photocell voltage 3.8> in the dark and approximately 0v in the light |
| 6A | Pump pressure more than 6 bar |
| 6B | Check oil supply to the pump |
| 6C | Drive coupling broken |
| 7A | Are ignition leads and electrodes ok and set correctly |
| 8A | Does burner light or green 0.5 seconds on / red 0.5 seconds before lockout |
| 8B | Contaminated fuel filter |
| 8C | Coil lead okay |
| 8D | Solenoid coil resistance |
| 8E | After 15 seconds from motor start 25 to 30 volts |
| 10A | Is the nozzle atomising the fuel |
| 10B | Needs new nozzle |
| 10C | Check oil pipe from pump to nozzle holder |
| 11A | Flame goes out then relights |
| 11B | Boiler or flue blocked |
| 11C | Ibalance flue and snorkel test |
| 11D | Balanced flues can recirculates gases causing recycling |
| 11E | Photocell voltage 3.8 in the dark and approximately 0v in light |
Worcester Bosch Error Code EA 229 or D5
If you’re seeing the error code EA 229 or D5 on your Worcester Bosch boiler, this means that the condensate pipe is frozen. This happens due to the condensate pipe running outside, however this is an issue that you could fix yourself if you feel confident enough.
