Safety first: Unplug the microwave before internal cleaning or service.

Step-by-step checks:

1. Clean the cavity: Steam and humidity sensors can be affected by heavy grease and food residue. Thoroughly clean the interior with a mild detergent and soft cloth, especially near any sensor grill or opening.
2. Locate the humidity sensor: On Grundig sensor models, the humidity sensor is often mounted near the top of the cavity or behind a small grill.
3. Inspect sensor area: Check for condensation, corrosion, or buildup on or around the sensor opening.
4. Check wiring: With the outer cabinet removed, trace the sensor wires to the control board and ensure connectors are secure.
5. Replace sensor if faulty: If cleaning and wiring checks do not clear E13, replace the humidity sensor with a compatible Grundig part.

If E13 remains after sensor replacement, the control PCB may have a defective sensor input circuit and should be replaced by a professional.

Microwave displays E13 and may not respond to some sensor-based auto programs.

Possible Causes