Remove the rear cover, locate the two sensor wires coming to the control board and measure the sensor resistance. It suppose to be about 1100 Ohms at the room temperature.
If the reading is correct then the control board has to be replaced. Unfortunately this part is no longer available.
If the reading is wrong then located the sensor plug (where it's coming through the back panel), unplug it and measure the sensor resistance at this plug.
If the reading is wrong then replace the sensor.
If the reading is correct then the problem is a bad wire harness and/or sensor plug.
- The part number for the oven sensor is
AP2023670
Gene.