Microwave shows F18 and stops heating when using sensor cooking or auto programs that rely on humidity detection.

Safety first: Unplug the microwave before accessing internal sensors.

• Step 1 – Clean cavity and sensor area: Wipe down the interior, especially around the sensor opening (often on the top or side wall). Remove grease and food residue that may block steam from reaching the sensor.
• Step 2 – Test manual modes: Check if standard timed microwave heating works normally. If only sensor programs fail with F18, the issue is likely limited to the humidity sensor circuit.
• Step 3 – Locate sensor (advanced): Remove the outer cabinet and trace the small sensor module mounted near the cavity wall. Inspect its wiring harness and connector.
• Step 4 – Reseat and inspect: Disconnect and reconnect the sensor plug. Look for corrosion or moisture damage.
• Step 5 – Replace sensor: If F18 persists, replace the humidity sensor with the correct Indesit part. If a new sensor does not resolve the error, the control board may be at fault.

Tip: Avoid covering the sensor area with plastic wrap or large dishes during sensor cooking.