Worcester Bosch

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 customer service helpline number

Best calling hours
09:00-18:00 GMT
Main Address
Head Office
Bosch Group
Cotswold Way

Worcester Boiler Error Codes

Listed below is a list of the most common fault codes most Worcester / Worcester Bosch Greenstar Boilers.

The alpha numeric code on your boiler indicates the one of the following faults

Error Code Probable cause
EA A Failure of 4 ignition attempts has occured. The boiler then suspends for 30 seconds before a further attempts are made.
EA The pilot light has been extinguished.

This could be caused by;

  • Moisture has entered the sump due to a blocked condensate trap
  • Liquid has collected in the basin.
  • Strong wind have entered the flue and extinguished the pilot light
EA Gas valve coil has broken or disconnected
EA The Pilot light has not established during the first 4 seconds ignition period
EA There is a problem where the pump is not detecting water – Check the pressure gauge and re pressurise to the green area or 1 bar.
9A The Wrong HCM unit has been fitted
9U Problem with the code plug.  The plug might be faulty or
B7 Replace control board
C6 The fan is either;

  • Running too fast
  • Running too slow
C7 Fan not running / Fan not running or airflow blocked
D1 Sensor wet or damaged (the boiler will block for 300 seconds before this condition)
D1 Sensor disconnected or damaged (the boiler will block for 300 seconds before this condition)
D1 Boiler overheating problem
E2 Flow sensor had been shorted or damaged
E2 Flow sensor dysfunctional or damaged
E5 The Primary flow sensor has overheated
E9 The heat exchanger has overheated.
This temperature usually exceeds 105°C
E9 Maximum temperature sensor on the primary heat exchanger has stopped functioning
E9 If the heat exchanger is new, the fault may be that the heat exchanger has not been recognised
E9 The flue gas thermostat has overheated