E18

SMEG Humidity / Steam Sensor Fault (Sensor Cooking Models)

Microwave displays E18; occurs when using sensor cooking or auto programs.

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

Failed humidity sensor, Blocked sensor port with grease or food residue, Wiring fault to sensor, Control PCB sensor input failure

How to Fix / Troubleshooting

Safety: Unplug the microwave before cleaning inside the cavity.

Cleaning the sensor area:

Locate the humidity/steam sensor port (often a small grille or opening on the cavity wall or ceiling; refer to the SMEG manual).
Clean the area gently with a soft cloth and mild detergent to remove grease and residue. Do not use abrasive cleaners.
Ensure the cavity is dry before use.

Reset and test:

Unplug for 5–10 minutes, then plug back in.
Test a basic manual power level program. If manual cooking works but sensor programs trigger E18, the sensor is likely faulty.

Technician checks:

Test the humidity sensor according to SMEG specifications.
Inspect wiring and connectors between the sensor and control PCB.
Replace the sensor or control PCB as required.

Repair Difficulty

Hard 4/5

Required Part

Humidity Sensor

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