Microwave stops mid-cycle and displays E05; may restart after cooling or power reset.

Safety first: Unplug the microwave before servicing. Avoid the high-voltage section.

Step-by-step checks:

• 1. Locate the cavity sensor: On many Grundig microwaves, the cavity temperature sensor (thermistor) is mounted on the top or side of the cooking cavity, accessible from inside the cabinet.
• 2. Inspect wiring: With the outer cabinet removed, trace the small-gauge wires from the sensor to the control board. Check for pinched, cut, or burnt insulation.
• 3. Check connector: Disconnect the sensor plug from the control PCB and inspect for corrosion or loose pins. Clean gently and reconnect firmly.
• 4. Test sensor resistance: Using a multimeter, measure the resistance of the thermistor at room temperature. Compare to the expected value from the service documentation (commonly in the tens of kilo-ohms). A reading of 0 Ω (short) or infinite (open) indicates a failed sensor.
• 5. Replace faulty sensor: If the sensor is out of specification, replace it with a Grundig-compatible cavity temperature sensor. Secure it firmly to the cavity wall or bracket as originally installed.

If the sensor and wiring test correctly but E05 persists, the control PCB's sensor input circuit may be defective and should be replaced by a technician.