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Error code reference

LG Oven Error Code F-2

Upper oven thermistor is shorted for over 1 minute after cook starts.

LG codesLG oven codes

Upper oven thermistor is shorted for over 1 minute after cook starts.

First step from the service manual

Check the thermistor using test mode 4.Diagnosis; verify sensor value is 70°F–90°F at room temperature. If not, power off and measure thermistor resistance at CN04 pin 3,4 — normal is approximately 1.09 kΩ.

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

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What F-2 means on a LG oven

The F-2 error code on an LG oven indicates that the upper oven thermistor has been detected in a shorted condition for more than one continuous minute after a cook cycle begins. The thermistor is a temperature-sensing resistor embedded in the oven cavity that feeds resistance-based temperature data to the control board. When the thermistor shorts, its resistance drops abnormally low, causing the control board to receive an inaccurate or invalid temperature signal. Rather than allowing the oven to operate blind to actual cavity temperature, the board triggers F-2 and halts the cooking process as a protective measure.

The thermistor circuit connects to the main control board through connector CN04, specifically at pins 3 and 4. At room temperature (roughly 70 to 90 degrees Fahrenheit), a properly functioning thermistor should read approximately 1.09 kΩ of resistance. A shorted thermistor will read significantly below this value, often near 0 Ω, indicating a direct electrical short either within the sensor body itself or along the wiring harness between the sensor and the control board.

Common causes include a failed thermistor due to heat exposure or physical damage, a pinched or melted wire in the sensor harness, or moisture intrusion causing a short in the connector or wiring. Diagnosis should begin with LG test mode 4, which displays a live sensor value that should fall between 70 and 90 degrees Fahrenheit at ambient room temperature. If the displayed value is outside this range, the next step is to power the unit off and measure resistance directly at CN04 pins 3 and 4 with a multimeter to isolate whether the fault is in the sensor or the wiring.

Source: manufacturer service documentation.

Common causes of F-2

  1. 01

    Failed upper oven thermistor

    Part replacement

    The thermistor itself has internally shorted due to heat cycling, physical damage, or age. A resistance reading well below 1.09 kΩ at CN04 pins 3 and 4 at room temperature confirms a failed sensor.

  2. 02

    Pinched or damaged thermistor wiring harness

    Part replacement

    The wiring between the thermistor and the control board can become pinched, melted, or chafed against the oven cavity, causing a short to ground or a short between the two sensor wires. Visually inspect the harness for burn marks, cuts, or areas where insulation has worn away.

  3. 03

    Corroded or shorted connector at CN04

    Wiring / connection

    Moisture or grease intrusion at the CN04 connector on the control board can bridge pins 3 and 4, simulating a shorted thermistor. Inspect the connector for discoloration, corrosion, or debris and clean or replace as needed.

  4. 04

    Control board misreading thermistor signal

    Part replacement

    In less common cases, the control board itself may be faulty and incorrectly interpreting a normal thermistor signal as a short. This should only be considered after the thermistor and wiring have been confirmed good through direct resistance measurement at CN04.

See the test procedure for each cause

Frequently asked questions about F-2

What does F-2 mean on a LG oven?
The F-2 error code means the upper oven thermistor has been detected in a shorted state for more than one minute after a cook cycle starts. The thermistor is the temperature sensor inside the oven cavity that tells the control board how hot the oven is. When this sensor shorts out, the board cannot accurately read oven temperature and shuts down cooking to protect the appliance. The fault points to the thermistor, its wiring harness, or the connector at CN04 pins 3 and 4 on the control board.
Can I fix the F-2 error on my LG oven myself?
A knowledgeable DIYer can diagnose F-2 using a multimeter to check resistance at CN04 pins 3 and 4, where a normal reading is approximately 1.09 kΩ at room temperature. If the thermistor reads near 0 Ω or well outside the normal range, replacing the sensor is a manageable repair for someone comfortable working with oven components. However, if the wiring harness or control board is involved, repairs become more complex and may warrant professional service.
Is it safe to use my LG oven when F-2 is displayed?
No, you should not attempt to use the oven while F-2 is active. The error means the control board cannot reliably monitor upper oven temperature, which creates a risk of uncontrolled overheating. The oven is designed to halt operation when this fault is present, and bypassing or ignoring it could be a safety hazard.
Will resetting my LG oven clear the F-2 error?
Cycling power to the oven may temporarily clear the F-2 code, but the error will return once a cook cycle starts if the underlying thermistor fault is still present. The code is triggered after the shorted condition persists for over one minute during cooking, so the root cause must be repaired to permanently resolve it. A reset should only be used as part of the diagnostic process, not as a fix.
How much does it cost to repair an LG oven F-2 error?
If the thermistor itself is the problem, parts and labor typically range from around $100 to $250 depending on your location and service provider. If the wiring harness needs repair or replacement, costs may fall in a similar range. A control board replacement, which is the least likely cause, can range from $200 to $400 or more including labor.

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