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Source-backed error-code guide

Reviewed

LG Range F4 / F5 Error Code

F4/F5 point to the lower-oven temperature-sensing system but do not prove the thermistor itself has failed. Record the code, let the appliance cool, and use LG’s supported reset once before requesting service.

Applies to LG range or oven with a lower oven

What the appliance detected

Detected condition

LG says F4 and F5 indicate a lower oven thermistor error.

What may contribute

Possible causes

  • A temperature-sensing condition detected in the lower oven circuit.
  • A temporary electronic condition that clears after the manufacturer-supported reset.
  • A thermistor, wiring, connector, or control-system issue requiring diagnosis if the code returns.

Start conservatively

Safe preliminary checks

Work in order and stop whenever a step is not supported by the documentation for your model.

  1. Stop cooking and preserve the code

    • Press CLEAR/OFF, allow the oven to cool, and photograph whether F4 or F5 was shown.
    • Record the exact model and which oven cavity was active.

  2. Look only for external warning signs

    • After cooling, check only for smoke, burning odor, scorching, or visible damage that can be observed without removing parts.
    • If any hazard is present, keep the appliance off and request qualified service.

  3. Use LG’s documented reset once

    • Retry the original function only when the oven is safe and cool enough for normal use.
    • If the code reappears, switch the range circuit breaker off for 30 seconds, restore power once, and request service if F4 or F5 returns.

Actions not recommended

  • Do not remove the oven sensor, back panel, control panel, or wiring covers.
  • Do not test thermistor resistance, live voltage, connectors, or control boards as a homeowner step.
  • Do not replace a sensor or control solely because F4 or F5 is displayed.

When to stop and request service

  • Request appliance service if F4 or F5 returns after LG’s supported reset.
  • Stop using the oven for uncontrolled heating, smoke, burning odor, sparking, or visible damage.
  • Provide the technician with the exact code, model number, and lower-oven context.

Documented source

Official information reviewed

Our summary is based on manufacturer support material and stays within the limits of that material.

Source reviewed by Appliance Help HQ: September 23, 2026.

Appliance Help HQ is an independent informational site and is not affiliated with or endorsed by LG.

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