GE Oven Error Code F20

F20 means the Electronic Range Control (ERC) or Machine Control board detected that the resistance on the upper oven sensor circuit exceeded the acceptable limit. The sensor is a small probe inside the upper oven cavity that monitors temperature. When its resistance reads too high, the board flags the fault and typically disables oven operation. The most common cause is a failed sensor or a wiring problem between the sensor and the control board.

No. When F20 is active, the oven cannot accurately monitor upper cavity temperature, which means it cannot regulate heat safely. Running the oven without a functional temperature sensor risks overheating and potential fire. Do not use the upper oven until the fault is diagnosed and the faulty component is repaired or replaced.

Disconnect power to the oven, then unplug the sensor connector from the wiring harness. Use a multimeter set to ohms and measure resistance across the two sensor terminals. At room temperature (approximately 70 degrees Fahrenheit), a good sensor should read close to 1080 to 1100 ohms. A reading significantly higher than this range, or an open circuit reading, confirms the sensor has failed and needs replacement. If the sensor reads correctly, check resistance at the board connector itself (CN300 pins 1 to 3 or J300 pins 1 to 2) to identify whether the wiring is adding resistance to the circuit.

Start by checking the resistance of the upper oven sensor circuit at CN300 pins 1 to 3 (W to W/BK) on the T012 ERC, or at J300 pins 1 to 2 (W to W/BK) on the Machine Control board. A properly functioning sensor typically reads around 1080 to 1100 ohms at room temperature. If resistance is out of range, replace the upper oven temperature sensor. If resistance reads correctly at the board connector, inspect the wiring harness and connectors for damage or corrosion. If all wiring checks out, the control board may need replacement.

If the fault is caused by the upper oven temperature sensor, the sensor part typically costs between $20 and $50, and replacing it is a manageable DIY repair for most homeowners since it usually involves removing two screws and one connector. If the wiring harness is damaged, repair costs vary but parts are generally inexpensive. A replacement ERC or Machine Control board is the most expensive scenario, often ranging from $150 to $300 for the part alone, plus labor if you hire a technician.