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Flash Sequence | Type of Fault | Fault | Possible Solutions |
Light OFF | No fault | No boiler demand - boiler is OK | |
Light ON | Heating demand on boiler- boiler is OK | ||
Group 1 Flashing codes | |||
1 | Locking | No ionisation detection after ignition | Failure of four ignition attempts, the boiler waits 30 seconds before another attempt is made. Reset the boiler by turning the control knob anticlockwise to the reset position. |
2 | Locking | Loss of ionisation signal during operation | An established flame has been extinguished. Reset the boiler by turning the control knob anticlockwise to the reset position. |
3 | Locking | Gas valve error | Gas valve coil disconnected. Check gas valve. Reset the boiler by turning the control knob anticlockwise to the reset position. |
4 | Locking | First safety timing error/ignition timing error | The flame was not established during the first four seconds of the ignition period. Reset the boiler by turning the control knob anticlockwise to the reset position. |
5 | Locking |
Ionisation detected after burner stopped Gas valve EV2 leak test failed Gas valve EV1 leak test failed Ionisation current detected before burner-start Gas valve error Ionisation sensor shorted |
Gas valve leaking. False flame detected. Reset the boiler by turning the control knob anticlockwise to the reset position. |
Flash Sequence | Type of Fault | Fault | Possible Solution |
Light OFF | No boiler demand - boiler is OK | ||
Light ON | Heating demand on boiler- boiler is OK | ||
Group 2 Flashing codes | |||
6 | Locking | Sensor test failed | On power up all safety sensors are checked, the check failed. Reset the boiler by turning the control knob anticlockwise to the reset position. |
7 | Locking | Safety temperature too high | The main heat exchanger has overheated. Maximum temperature 105°C. Reset the boiler by turning the control knob anticlockwise to the reset position. |
8 | Blocking | MAX safety thermostat activated | Flue gas thermostat overheat or APS activated |
9 | Locking | Return temperature too high | Boiler overheat. Reset the boiler by turning the control knob anticlockwise to the reset position. |
10 | Locking |
Flow temperature too high - Supply sensor exceeded 110°C |
Primary flow sensor overheated. Reset the boiler by turning the control knob anticlockwise to the reset position. |
Flash Sequence | Type of Fault | Fault | Possible Solution |
Light OFF | No boiler demand - boiler is OK | ||
Light ON | Heating demand on boiler- boiler is OK | ||
Group 3 Flashing codes | |||
11 | Locking | HCM (Heat Control Module) Defective | Incorrect, faulty, or missing HCM. Replace HCM with correct item Reset the boiler by turning the control knob anticlockwise to the reset position. |
12 | Locking |
Fan running too fast Fan running too slow No airflow after defined period of time Fan not running |
Defective fan or blocked air way. Reset the boiler by turning the control knob anticlockwise to the reset position. |
13 | Locking | Mains voltage interrupted after locking error | Reset the boiler by turning the control knob anticlockwise to the reset position. |
14 | Locking | Internal control board faults | Call Worcester, Bosch Group technical help-line 0330 123 3366 |
15 | Locking | All other faults | Miscellaneous Reset the boiler by turning the control knob anticlockwise to the reset position. |