Worcester boiler error codes

The Worcester company is part of the Bosch Group. It has recently introduced a new combined gas boiler Worcester Greenstar i, which is characterized by enhanced productivity, A-class energy performance and many other useful features. And refer to the table below for Worcester boiler error codes.

Worcester Greenstar Highflow 440 boiler error codes

Display Code:Fault description:Check, repair/replace as necessary:
A5Tank sensor faultTank sensor (8000 – 20000 ohms at room temperature). Wiring and connections to sensor.
A6Link faultCheck link 8 to 9 in connector ST3.
A7DHW sensor faultDHW sensor (8000 – 20000 ohms at room temperature). Wiring and connections to sensor.
A8Module failNight set back module TR212E and/or Roomstat TR2. Wiring and connections between modules.
b1Code plug not detectedCode plug version, condition and fitting. If OK replace control board.
C1Fan speed too lowFan harness and connections. Fan.
Otherwise replace control board.
d3Terminals 8-9 not shorted at connector ST7Safety overheat thermostat for underfloor heating system (if fitted).
Otherwise fit link.
d5Condensate pump failedMains supply to condensate pump. Condensate Pump unit.
Continuity of all cables to pump unit.
d6Tank overheatTank sensor is correctly fixed to tank Wiring and connections to sensor.
E2CH flow sensor faultCH flow sensor (8000 – 20000 ohms at room temperature).
Wiring and connections to sensor.
E9 (error solution E9)Safety overheat device trippedAll air vented.
Water pressure above minimum.
Leaks or blockage.
Condition and attachment of CH flow sensor.
Pump and associated wiring/connections.
Connections and wiring to overheat thermostat devices. Otherwise replace control board.
EAFlame not detectedGas present and at correct pressure. Combustion C02 level.
Condition of flue.
Ignition electrodes.
Ignition harness and connections. Flame sense harness.
Flame sense cables and connections. Gas valve.
Otherwise replace control board.
FOInternal errorTransformer.
All connections to control board. Otherwise replace control board.
F7Flame detected with no demand.Gas valve
Flame sense electrodes/cables Moisture on control board. Blocked condensate trap. Otherwise replace control board.
FAFlame detected after gas. Gas valve switched off.Cables and connections to gas valve. Condensate trap.
Flue (for blockages).
Otherwise replace control board.
FdReset button pressed by mistakePress reset button again.

Worcester GREENSTAR HIGHFLOW 440CDI ERP boiler error codes

Error codeDescription
A7Hot water NTC sensor defective.
A8Break in communication to weather compensating clip-in control or Greenstar Comfort IIRF
blCode plug not detected.
C6Fan speed too low.
E2CH flow NTC sensor defective.
E9Safety temp, limiter in CH flow has tripped.
EAFlame not detected.
Check, if it safe to do so:
• if gas is on in the house
• for frozen condensate pipe
• for blocked flue outlet
FOInternal error.
F7Flame detected even though boiler switched off.
FAFlame detected after gas shut off.
FdReset button pressed by mistake.

Worcester basic error codes

Locking Fault CodePossible Cause
9ABoiler has been fitted with incorrect Heat Control Module (HTM).
9UThe code plug could be faulty or not properly connected.
B7You need to replace the control board.
C6The system is running too fast or too slow.
C7Fan is not running or the airflow could be blocked.
D1Sensor could be wet, damaged or disconnected. The boiler will block for 300 seconds.
D1Boiler is overheating.
E2The Flow sensor has shorted, is damaged or disconnected.
E5The primary flow sensor has overheated.
E9 (error solution E9)The main heat exchanger has overheated as the main temperature is 150 degrees.
E9 (error solution E9)Maximum temperature sensor on the main heat exchanger cannot be recognised or has failed.
E9 (error solution E9)The flue gas thermostat has overheated.
EAFailure after four ignition attempts. The boiler will wait 30 seconds before another attempt is made.
EAA flame has been extinguished due to either moisture in the sump, a blocked sump or strong wind in the flue.
EAGas valve coil has been disconnected.
EAFlame has not extinguished within first 4 seconds of ignition.
EAThere is an error as the pump is not detecting water. Check the pressure gauge and re-pressurise to 1 bar.

Blocking Fault Code   Possible Cause
   A1Little or no water in the system- Check pressure gauge and re-pressurise to 1 bar.
   C1Fan has stopped.
   EANo flame is detected and so the boiler will block during 4 attempts before going to Locking fault.
   EFThe boiler is operating at minimum burner load and there is higher flow temperature of 18 degrees.
   260Sensor has been disconnected or there is no water content- check pressure gauge and repressurise to 1 bar.