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Worcester Bosch Greenstar 4000 Combi fault codes

58 codes from the Worcester Bosch manual for the Greenstar 4000 Combi gas boiler. Pick one for what it means, the likely causes and where to start.

CodeWhat it means
1013Max. combustion point reached (the maximum burner time is reached)
1021Cylinder charging or hot water temperature sensor faulty
1037Outside temp. sensor faulty - heating backup operation active
1065System pressure sensor faulty or not connected
1068Outside temp. sensor or lambda probe faulty
1073Short-circuit at flow temp. sensor
1074No signal from flow temperature sensor
1075Heat exchanger temp sensor short circuit
1076Heat exchanger temp sensor disconnected
2085Internal fault
214Fan shut down during safety time
224Maximal flue gas thermostat or heat exchanger maximal thermostat has activated (blocking)
228Flame signal without flame present
234Gas valve electrical fault
235Conflicting versions of boiler electr. and boiler identification
238Boiler electronics faulty
242Boiler electr. system fault
245System fault boiler electronics / basic controller
249System fault boiler electronics / basic controller
250System fault boiler electronics / basic controller
251System fault boiler electronics / basic controller
252System fault boiler electronics / basic controller
253System fault boiler electronics / basic controller
254System fault boiler electronics / basic controller
258System fault boiler electronics / basic controller
259System fault boiler electronics / basic controller
262System fault boiler electronics / basic controller
263System fault boiler electronics / basic controller
269Flame monitoring
281Pump stuck or running in air
283Burner starting
284Opening air/gas ratio control valve/oil solenoid valves
2910Fault in flue system
2915Boiler electr. system fault (fan keeps running after post purge)
2916Boiler electr. system fault (gas valve detected open during post-purge)
2923Boiler electr. system fault (unexpected feedback from modulating gas valve)
2927Flame failed during burner operation
2928Internal fault
2931System fault boiler electronics / basic controller (illegal instruction)
2940System fault burner control unit (low voltage)
2948No flame signal with low output
2949No flame signal with high output
2950No flame signal following starting procedure
2951Loss of flame too many times
2952Internal fault when testing the ionisation signal
2957Boiler electr. system fault
2961No fan signal available
2962No fan signal available
2963The heat exchanger sensor or both supply and heat exchanger sensors are defect
2964Flow rate in heat exchanger too low
2965Flow temperature too high
2966Flow temperature rise in heat exchanger too rapid
2967Temperature difference between supply sensor and heat exchanger sensor too large
2970Pressure drop in heating system too rapid
2972Mains voltage too low
306Flame signal after closing the fuel supply
3071Comfort + II RF communication fault
363System fault boiler electronics / basic controller