E12
Baxi
Internal Communication / Sensor Circuit Fault
Boiler intermittently locks out with E12, may relate to sensor or PCB communication issues
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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
Intermittent wiring connection on sensor harness, Faulty Baxi PCB, Moisture ingress on control board, Incorrect earthing or supply voltage issues
How to Fix / Troubleshooting
Safety first: Isolate power before removing any covers.
User checks:
- Ensure the fused spur is supplying a stable 230V supply (no loose plug or switch).
- Power cycle the boiler and monitor if the fault is weather-related (e.g. heavy condensation or leaks nearby).
Professional actions:
- An engineer will inspect the PCB for signs of damage or moisture, check all sensor connections, and test supply voltage and earthing.
- They may need to replace the PCB and reconfigure it for your specific Baxi model.
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Repair Difficulty
Hard
4/5
Required Part
Main PCB (Control Board)
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