Worcester Bosch boiler fault codes
Codes starting with EA indicate problems related to ignition.
EA
| EA | Flame not established during the first 4 seconds ignition period |
| EA 227 Ign | This is an ignition problem. If you press Reset, the issue may be resolved |
| EA | An established flame has been extinguished. This could be caused by: moisture in the sump, due to a blocked sump/condensate trap, or a strong wind into the flue |
| EA | Gas valve coil disconnected |
| EA | Failure of four ignition attempts. The boiler waits 30 seconds before another attempt is made |
| EA | There is an error where the pump is not detecting water – check pressure gauge and repressurise to 1 bar |
| EA | No flame is detected. This indicates that the boiler has failed to ignite, or the flame sensor is not detecting a flame. The boiler will block during 4 attempts before going to Locking fault |
Other codes
| 9A | Incorrect HCM fitted |
| 9U | Problem with the code plug (faulty or not connected) |
| A1 | Little or no water in the system – check pressure gauge and repressurise to 1 bar |
| B7 | Replace control board |
| C1 | Fan has stopped |
| C6 | Fan running too fast or 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 | Boiler overheat |
| E2 | Flow sensor shorted, disconnected or damaged |
| E5 | Primary flow sensor overheated |
| E9 | The main heat exchanger has overheated. Maximum temperature 105°C |
| E9 | Maximum temperature sensor on the main heat exchanger has failed or has not been recognised |
| E9 | Flue gas thermostat overheat |
| EF | The boiler is operating at minimum burner load and there is a greater than 18°C Flow & Return temperature difference |
| F1 | Low water pressure: This fault code suggests that the water pressure in the system is too low. This could be due to a leak or an issue with the pressure relief valve. |
| F2 | High water pressure: This fault code suggests that the water pressure in the system is too high. This could be due to a faulty pressure relief valve or a blocked pressure gauge. |
| F4 | Ignition fault: This indicates that the boiler has failed to ignite after three attempts. This could be due to a problem with the gas supply or the ignition system. |
| F5 | Overheating: This fault code indicates that the boiler is overheating. This could be due to a problem with the thermostat or a blockage in the system. |
| F9 | PCB fault: This fault code indicates a problem with the printed circuit board (PCB) of the boiler. This could be due to a fault in the wiring or a problem with the PCB itself. |
| 260 | Sensor disconnected or no water content – check pressure gauge and repressurise to 1 bar |
If there is no code, this may indicate that there is an air lock or reduced water content. In this case, you should check the pressure gauge and repressurise to 1 bar.