E18 appears and the heater may not start or may shut down during operation.

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

Supply voltage outside Baxi specification, Loose mains terminal connections, Internal power supply fault on PCB, Neutral/earth issues

Safety: Mains voltage is dangerous. If you are not competent, do not open the electrical compartment.

User-level:

Check supply: Ensure the heater is connected to a stable power source and that no other heavy loads are causing voltage dips.
Inspect plug/fuse (if applicable): Check the fuse rating and condition in the fused spur or plug.

Professional: An electrician or technician should check terminal tightness, measure supply voltage, and test the PCB power supply section.

Hard 4/5

Internal Power Supply on PCB

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