E12
Dimplex
Communication Fault Between Boiler PCB and Room Controller
Boiler displays E12; no heating; room thermostat appears to call for heat but boiler does not respond
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Broken communication cable between Dimplex boiler and Dimplex room controller, Incorrect wiring on low-voltage terminals, Faulty Dimplex room thermostat or programmer, Firmware incompatibility between controller and boiler PCB
How to Fix / Troubleshooting
Safety first: Isolate power before accessing wiring terminals.
User checks:
- Controller power: Ensure the Dimplex room controller or programmer has power (screen lit, time displayed).
- Settings: Confirm the controller is set to heating ON and that schedules are correct.
- Reset both units: Power off the boiler and controller (if separate), wait 30 seconds, then power back on and re-establish communication if your model supports pairing.
Professional actions:
- Check continuity and polarity of the communication cable between the Dimplex boiler PCB and controller.
- Replace the Dimplex room controller or boiler PCB if one is confirmed faulty.
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Repair Difficulty
Medium
3/5
Required Part
Dimplex room controller / thermostat
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