Error code reference

GE Oven Error Code F20

Upper oven sensor circuit fault

GE codesGE oven codes

Upper oven sensor circuit fault - resistance threshold exceeded on upper oven sensor (T012 ERC or Machine Control).

First step from the service manual

Check resistance of oven sensor circuit on ERC (T012) at CN300 pin 1 to 3 W to W/BK, or on Machine Control board connector J300 pins 1 to 2 W to W/BK.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F20 means on a GE oven

The F20 error code on a GE oven indicates that the Electronic Range Control (ERC) or Machine Control board has detected a resistance reading on the upper oven sensor circuit that exceeds the acceptable threshold. The fault is monitored at connector CN300 pins 1 to 3 (W to W/BK) on the T012 ERC, or at connector J300 pins 1 to 2 (W to W/BK) on the Machine Control board. When the resistance value climbs beyond the expected range, the control interprets this as a circuit fault and halts normal oven operation.

For homeowners, this means the electronic brain of your oven detected a problem with the temperature sensor in the upper oven cavity. The sensor is a small probe mounted inside the oven that tells the control board how hot the oven is. When its electrical resistance reads too high, the board can no longer trust the temperature data and shuts down to prevent overheating or unsafe operation.

This fault is most often caused by a failed oven temperature sensor, damaged wiring between the sensor and the control board, or a loose or corroded connector at the board itself. In less common cases, the control board may be misreading an otherwise healthy circuit.

Source: manufacturer service documentation.

Common causes of F20

  1. 01

    Failed upper oven temperature sensor

    Part replacement

    The upper oven sensor (RTD probe) has drifted out of its normal resistance range or failed open, sending a reading to the ERC or Machine Control board that exceeds the acceptable threshold. This is the most common cause of F20 and typically requires sensor replacement.

  2. 02

    Damaged or broken wiring harness between sensor and control board

    Part replacement

    The W to W/BK wires running from the upper oven sensor to CN300 or J300 on the control board can fray, burn, or break, increasing circuit resistance beyond the fault threshold. Inspect the full length of the harness for heat damage, pinching, or breaks.

  3. 03

    Loose or corroded connector at CN300 or J300

    Wiring / connection

    A poor connection at pin 1 to 3 on CN300 (T012 ERC) or pins 1 to 2 on J300 (Machine Control board) can introduce resistance into the circuit and trigger F20. Reseating or cleaning the connector may resolve the fault without replacing parts.

  4. 04

    Faulty ERC (T012) or Machine Control board

    Part replacement

    If the sensor and wiring harness both test within the correct resistance range, the control board itself may be misreading the circuit. A failed input circuit on the ERC or Machine Control board can falsely report an F20 fault.

See the test procedure for each cause

Frequently asked questions about F20

What does F20 mean on a GE oven?
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.
How do I fix the F20 error code on my GE oven?
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.
Is it safe to use my GE oven while the F20 error code is displayed?
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.
How much does it cost to fix an F20 error on a GE oven?
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.
How do I test the upper oven sensor to diagnose F20 on a GE oven?
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.

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