Boiler shows E09, no heating or hot water, may occur after component replacement or wiring work.
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.
Possible Causes
How to Fix / Troubleshooting
Safety first: Isolate the boiler from the mains before removing the front cover or accessing the electronics.
User-level checks:
- Turn off the boiler at the mains for 2–3 minutes, then power back on to perform a hard reset.
- Check that no external controls (e.g. OpenTherm thermostat) have been recently changed or miswired.
Technical checks (qualified personnel):
- Verify correct mains polarity, earth continuity, and supply voltage at the boiler terminals.
- Inspect all multi-pin connectors on the main PCB for secure fit and signs of overheating or corrosion.
- Check low-voltage harnesses to sensors, fan, and gas valve for continuity and shorts.
- If all peripheral components test correctly, replace the main PCB with the correct Chaffoteaux part number and transfer any configuration links or jumpers as per service manual.
After PCB replacement, perform commissioning checks and parameter setup according to Chaffoteaux instructions.
Repair Difficulty
Required Part
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