| A8 and fault indicator LED are flashing. Bus communication to the programmer interrupted (set value not received) | |||
|---|---|---|---|
| Check | Action | ||
| 1. | â–¶ Switch off the appliance. â–¶ Disconnect the appliance power. â–¶ Remove the upper section of the programmer mount and slide the programmer out of the wall mount. â–¶ Check the wiring between the programmer and the appliance. Are terminals B being used, the cen- tre terminal must not be used for bus connections. Check that terminals B are con- nected on the appliance and pro- grammer. â–¶ Is there continuity | yes: | A8? go to 2 |
| no: | Wire up or correct bus cable. â–¶ Reconnect appliance power. â–¶ Switch on appliance. A8? go to 2 |
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| 2. | Where multiple bus modules are installed: â–¶ Check the wiring between bus modules and the branch box. â–¶ Ensure that the B terminals are employed. â–¶ Switch off the appliance. â–¶ Disconnect the appliance power. B Is there continuity | yes: | A8? go to 3 |
| no: | â–¶ Cable between bus module and branch box is defective. â–¶ Repair or replace cable. â–¶ Reconnect appliance power. B Switch on appliance. A8? go to 3 |
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| 3 | Where multiple bus modules are installed: â–¶ Check the wiring between branch box and the programmer. â–¶ Ensure that the B terminals are employed. â–¶ Switch off the appliance. â–¶ Disconnect the appliance power. B Is there continuity | yes: | A8? go to 4 |
| no: | â–¶ Cable between the branch box and programme is defective. â–¶ Repair or replace cable. â–¶ Reconnect appliance power. B Switch on appliance. A8? go to 4 |
||
| 4. | Has the programmer been replaced? | yes: | A8? go to 5 |
| no: | â–¶ Switch off appliance â–¶ Disconnect electrical power B Replace programmer â–¶ Reconnect appliance power B Switch on appliance A8? go to 5 |
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| 5. | Has the bus module been replaced | yes: | A8? go to 6 |
| no: | â–¶ Switch off appliance â–¶ Disconnect electrical power B Replace bus module â–¶ Reconnect appliance power B Switch on appliance A8? go to 5 |
||
| 6. | The PCB control board is faulty | â–¶ Reconnect electrical power â–¶ Switch on appliance â–¶ Make a note of the service function settings B Switch off appliance â–¶ Disconnect electrical power â–¶ Change PCB control board â–¶ Reconnect electrical power â–¶ Switch on appliance â–¶ Restore service settings noted previously |
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Worcester Bosch A8 Fault Code Repair
Welcome to the fault-codes section of this site. The following table or page contains the information required to help repair and diagnose the fault codes being shown on the boiler display. You may be guided through the fault finding sequence or steps, for rectifying your boiler with this fault code. Suggested repair solutions may be provided by a link to a repair page. NB Some fault codes are only applicable to a specific range of boilers only.
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