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Error code reference

LG Range Error Code F9

Oven no heating

LG codesLG range codes

Oven no heating — with starting temperature of 130°F or less and oven door closed, the oven temperature does not rise more than 10°F compared to starting temperature within 5 minutes after cooking starts (except Proof, Warm, and Easy Clean).

First step from the service manual

Check electrical wiring, igniter resistance, and oven sensor.

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

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
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What F9 means on a LG range

The F9 error code on an LG range indicates that the oven has failed to reach a minimum temperature threshold within the first five minutes of a cooking cycle. Specifically, the control board monitors the oven temperature at startup and expects to see at least a 10°F rise from the starting temperature within five minutes, provided the starting temperature is 130°F or below and the oven door is closed. If that temperature increase does not occur, the board logs F9 and halts the heating cycle. This monitoring applies to all cooking modes except Proof, Warm, and Easy Clean, which operate at lower temperatures or have different heating expectations.

The three primary systems involved in this diagnostic are the electrical wiring to the heating components, the igniter (on gas models), and the oven temperature sensor. On a gas range, the igniter must draw sufficient current to open the gas valve and sustain ignition. A weak or failing igniter may glow but fail to reach the amperage required to open the valve, resulting in no gas flow and no temperature rise. On electric models, a failed bake element would produce the same symptom. The oven sensor (also called the RTD sensor) reports temperature back to the control board, and a sensor with incorrect resistance values will cause the board to misread the oven temperature, potentially triggering a false F9 or masking an actual heating failure.

Diagnosing F9 requires checking each subsystem in sequence. Start by inspecting all wiring connections to the igniter, bake element, and oven sensor for corrosion, loose terminals, or heat damage. Measure the resistance of the oven sensor, which typically should read near 1080 ohms at room temperature. Check the igniter for proper resistance and confirm it glows at full brightness during a call for heat. If wiring and the sensor check out, the igniter or bake element is the most likely failed component.

Source: manufacturer service documentation.

Common causes of F9

  1. 01

    Weak or failed igniter (gas models)

    Part replacement

    The igniter must draw enough current to open the gas valve. If it glows dimly or fails entirely, no gas is released and the oven produces no heat. Inspect the igniter visually during a heat cycle and test its resistance.

  2. 02

    Failed bake element (electric models)

    Part replacement

    A burned-out or shorted bake element will not generate heat, causing the oven temperature to remain flat after startup. Visually inspect the element for cracks, blistering, or burn marks.

  3. 03

    Faulty oven temperature sensor

    Part replacement

    The oven sensor reports temperature to the control board. If its resistance is out of range, the board may incorrectly read the oven as not heating or may fail to trigger the heating cycle properly. The sensor should read approximately 1080 ohms at room temperature.

  4. 04

    Loose or damaged wiring connections

    Wiring / connection

    Wiring terminals leading to the igniter, bake element, or oven sensor can loosen or corrode over time, interrupting the circuit. Inspect all connectors in the oven cavity and behind the rear panel for heat damage or poor contact.

  5. 05

    Defective oven control board

    Part replacement

    If wiring, the igniter or element, and the sensor all test within spec, the control board itself may not be sending the proper signal to initiate or sustain heating. This is the least common cause and should be diagnosed only after ruling out all other components.

See the test procedure for each cause

Frequently asked questions about F9

What does F9 mean on a LG range?
F9 on an LG range means the oven failed to raise its temperature by at least 10°F within the first five minutes of a cooking cycle, starting from a temperature of 130°F or below with the door closed. The control board interprets this as a heating failure and stops the cycle to prevent unsafe operation. The code points to a problem with the igniter, bake element, oven temperature sensor, or the wiring connecting these components.
Can I fix the F9 error myself?
Some steps, like inspecting wiring connections or testing the oven sensor resistance with a multimeter, are within reach for a confident DIYer. However, replacing an igniter, bake element, or control board involves working near gas lines or high-voltage components, which carries real safety risk. If you are not comfortable working with these systems, hiring a qualified appliance technician is the safer choice.
Will resetting the range clear the F9 error code?
Resetting the range by unplugging it or cutting power at the breaker may temporarily clear the F9 code, but it will return as soon as you attempt another cook cycle if the underlying problem has not been fixed. The code is triggered by a live performance check during each heating cycle, not stored as a one-time fault that can simply be erased.
Is it safe to use my LG range while the F9 code is showing?
You should not continue using the oven while F9 is active. On a gas model, a failing igniter could allow gas to flow without igniting, which is a serious safety hazard. On any model, operating the appliance with a known heating failure can place additional stress on other components. The surface burners on a gas range may still function normally, but the oven should remain out of service until repaired.
How much does it cost to repair an F9 error on an LG range?
Repair costs vary depending on which component has failed. A replacement oven igniter typically runs between $20 and $80 for the part, while a bake element can range from $30 to $100. An oven temperature sensor generally costs between $20 and $60. If you add professional labor, total repair costs commonly fall in the range of $150 to $350, though a control board replacement would push costs higher.

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