Worcester Bosch Boiler Error Codes
As Birmingham-based Worcester Accredited Installers, our engineers are ready to assist with diagnosing and resolving any Worcester Bosch boiler fault codes. This handy error guide can help you identify potential issues before reaching out to one of our experts. By using the table below, you’ll find information on the most common fault codes for Worcester Bosch CDI and Greenstar models, along with tips for diagnosing and solving the problem. Be sure to refer to your specific model's manual for more detailed information.
Worcester Bosch Greenstar
i Series, Si Compact, CDi Classic, CDi Compact, 4000 Series, Highflow CDi
EA 227 – No Flame Detected (Ignition Failure)
Cause: The boiler has failed to ignite, possibly due to a gas supply issue, faulty ignition electrode, or blocked condensate pipe.
Solution: Ensure the gas supply is on and other gas appliances are working. Check for a frozen or blocked condensate pipe. Try resetting the boiler.
Cause: The boiler has failed to ignite, possibly due to a gas supply issue, faulty ignition electrode, or blocked condensate pipe.
Solution: Ensure the gas supply is on and other gas appliances are working. Check for a frozen or blocked condensate pipe. Try resetting the boiler.
A21 – Wireless RF Controller Communication Error
Cause: The boiler has lost connection with the RF thermostat or controller.
Solution: Re-pair the RF controller. Check batteries and signal range.
Cause: The boiler has lost connection with the RF thermostat or controller.
Solution: Re-pair the RF controller. Check batteries and signal range.
C6 215 – Fan Speed Too High/Low
Cause: Fan speed is outside expected range. Could be due to a blocked flue, faulty fan, or PCB issue.
Solution: Check flue for blockages. Test fan and wiring. Consult engineer if persistent.
Cause: Fan speed is outside expected range. Could be due to a blocked flue, faulty fan, or PCB issue.
Solution: Check flue for blockages. Test fan and wiring. Consult engineer if persistent.
D1 286 – Flow Sensor Fault
Cause: The flow temperature sensor is faulty or disconnected.
Solution: Check sensor wiring and replace if needed.
Cause: The flow temperature sensor is faulty or disconnected.
Solution: Check sensor wiring and replace if needed.
E5 332 – No Primary Water Flow
Cause: Poor circulation due to pump failure, airlock, or system blockage.
Solution: Bleed radiators, check pump operation, ensure adequate pressure.
Cause: Poor circulation due to pump failure, airlock, or system blockage.
Solution: Bleed radiators, check pump operation, ensure adequate pressure.
E9 219 – Return Temperature Sensor Fault
Cause: Sensor error or wiring issue.
Solution: Inspect wiring and sensor. Replace sensor if necessary.
Cause: Sensor error or wiring issue.
Solution: Inspect wiring and sensor. Replace sensor if necessary.
E9 220 – Flow Temperature Sensor Fault
Cause: Flow sensor is faulty or reading incorrectly.
Solution: Test sensor and connections. Replace if defective.
Cause: Flow sensor is faulty or reading incorrectly.
Solution: Test sensor and connections. Replace if defective.
E9 221 – Maximum Temperature Exceeded
Cause: The boiler has overheated.
Solution: Check for system blockage, pump operation, and air in the system.
Cause: The boiler has overheated.
Solution: Check for system blockage, pump operation, and air in the system.
E9 224 – Overheat Lockout (Dry Fire)
Cause: Lack of water circulation leading to overheating.
Solution: Refill system to correct pressure. Check for pump failure or airlocks.
Cause: Lack of water circulation leading to overheating.
Solution: Refill system to correct pressure. Check for pump failure or airlocks.
H07 – Controller Communication Failure
Cause: Faulty communication between boiler and external control device.
Solution: Check wiring, connections, and controller setup.
Cause: Faulty communication between boiler and external control device.
Solution: Check wiring, connections, and controller setup.
9A 362 – Coding Card Missing or Incorrect
Cause: The boiler’s internal configuration card is not detected or mismatched.
Solution: Check that coding card is correctly inserted. Replace if damaged.
Cause: The boiler’s internal configuration card is not detected or mismatched.
Solution: Check that coding card is correctly inserted. Replace if damaged.
Worcester Bosch Greenstar 8000
Life & Style Series
EA 227 – No Flame Detected (Ignition Failure)
Cause: The boiler has failed to ignite, possibly due to a gas supply issue, faulty ignition electrode, or blocked condensate pipe.
Solution: Ensure the gas supply is on and other gas appliances are working. Check for a frozen or blocked condensate pipe. Try resetting the boiler.
Cause: The boiler has failed to ignite, possibly due to a gas supply issue, faulty ignition electrode, or blocked condensate pipe.
Solution: Ensure the gas supply is on and other gas appliances are working. Check for a frozen or blocked condensate pipe. Try resetting the boiler.
A21 – Wireless RF Controller Communication Error
Cause: The boiler has lost connection with the RF thermostat or controller.
Solution: Re-pair the RF controller. Check batteries and signal range.
Cause: The boiler has lost connection with the RF thermostat or controller.
Solution: Re-pair the RF controller. Check batteries and signal range.
C6 215 – Fan Speed Too High/Low
Cause: Fan speed is outside expected range. Could be due to a blocked flue, faulty fan, or PCB issue.
Solution: Check flue for blockages. Test fan and wiring. Consult engineer if persistent.
Cause: Fan speed is outside expected range. Could be due to a blocked flue, faulty fan, or PCB issue.
Solution: Check flue for blockages. Test fan and wiring. Consult engineer if persistent.
D1 286 – Flow Sensor Fault
Cause: The flow temperature sensor is faulty or disconnected.
Solution: Check sensor wiring and replace if needed.
Cause: The flow temperature sensor is faulty or disconnected.
Solution: Check sensor wiring and replace if needed.
E5 332 – No Primary Water Flow
Cause: Poor circulation due to pump failure, airlock, or system blockage.
Solution: Bleed radiators, check pump operation, ensure adequate pressure.
Cause: Poor circulation due to pump failure, airlock, or system blockage.
Solution: Bleed radiators, check pump operation, ensure adequate pressure.
E9 224 – Overheat Lockout (Dry Fire)
Cause: Lack of water circulation leading to overheating.
Solution: Refill system to correct pressure. Check for pump failure or airlocks.
Cause: Lack of water circulation leading to overheating.
Solution: Refill system to correct pressure. Check for pump failure or airlocks.
9A 362 – Coding Card Missing or Incorrect
Cause: The boiler’s internal configuration card is not detected or mismatched.
Solution: Check that coding card is correctly inserted. Replace if damaged.
Cause: The boiler’s internal configuration card is not detected or mismatched.
Solution: Check that coding card is correctly inserted. Replace if damaged.
H07 – Controller Communication Failure
Cause: Faulty communication between boiler and external control device.
Solution: Check wiring, connections, and controller setup.
Cause: Faulty communication between boiler and external control device.
Solution: Check wiring, connections, and controller setup.
2965 B – External Temperature Sensor Fault
Cause: The external temperature sensor is faulty or disconnected.
Solution: Inspect the sensor and its wiring. Replace if necessary.
Cause: The external temperature sensor is faulty or disconnected.
Solution: Inspect the sensor and its wiring. Replace if necessary.
2961 B – Flow Temperature Sensor Fault
Cause: The flow temperature sensor is faulty or disconnected.
Solution: Check the sensor and its connections. Replace if needed.
Cause: The flow temperature sensor is faulty or disconnected.
Solution: Check the sensor and its connections. Replace if needed.
2960 B – Return Temperature Sensor Fault
Cause: The return temperature sensor is faulty or disconnected.
Solution: Inspect the sensor and its wiring. Replace if necessary.
Cause: The return temperature sensor is faulty or disconnected.
Solution: Inspect the sensor and its wiring. Replace if necessary.
A41 – Control Unit Software Fault
Cause: Software error in the boiler's control unit.
Solution: Reset the boiler. If the fault persists, consult a qualified engineer.
Cause: Software error in the boiler's control unit.
Solution: Reset the boiler. If the fault persists, consult a qualified engineer.
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