How to Fix / Troubleshooting

Safety: Only work on electrical components if you are competent. Otherwise, call a qualified technician.

Check mains supply: Verify that the boiler's fused spur or plug is switched on and that the circuit breaker has not tripped.
Test socket: Plug another appliance into the same outlet to confirm power is present.
Internal fuse (technician):
- Isolate power and open the control box.
- Check the internal fuse(s) on the PCB and replace only with the exact type and rating specified by Junkers.
- If the new fuse blows immediately, locate and repair the underlying fault before further operation.
PCB replacement: If supply and fuses are good but the display remains dead, the main PCB may need replacement.

Boiler will not start at all; display is blank

Possible Causes