LG Oven F4 Error: Oven over-temperature safety shutdown
LG oven error — here’s what you need to know. The F4 error code on your LG oven indicates oven over-temperature protection — the cavity temperature has exceeded 650°F for more than 2 minutes during normal operation. This is a High severity issue. What Does F4 Mean on an LG Oven? F4 is LG’s over-temperature […]
~55%
DIY Fixable
From $80 (RTD sensor) — $400 (control board)
Typical Repair Cost
1–3 hours
Pro Repair Time
Quick Assessment
Answer to continue safely
Is it safe to keep using?
No. Do not use the oven for cooking until the cause of F4 is confirmed and repaired. A genuine over-temperature condition is a fire hazard; a false F4 from a bad sensor should still be corrected before regular use.
Can I reset the code?
Yes. Disconnecting power at the breaker for 5 minutes clears the F4 code. However, if the underlying sensor or relay fault is not repaired, F4 will return. A reset alone is not a repair.
When to stop immediately?
Stop if you notice: Stop using the oven immediately when F4 appears — continued operation with a runaway-heat fault risks a kitchen fire., Stop if you smell burning or see smoke from the oven cavity during a normal baking cycle before F4 appears..
Symptoms You May Notice
Food burns or scorches far sooner than the recipe indicates
Food placed in the oven chars, dries out, or burns significantly ahead of the expected cooking time, pointing to actual cavity temperatures well above the set point.
F4 code on display with oven heating stopped
The control panel shows F4 and the bake or broil element shuts off entirely as the built-in thermal protection activates.
Strong burning or acrid smell from oven interior
An unusual burning odor — distinct from normal cooking smells — comes from the oven cavity as temperatures rise well beyond the safe baking range.
Heating element stays on without cycling
During normal operation an oven element cycles on and off to hold set temperature; a stuck relay causes it to stay energized continuously, driving runaway heat.
Possible Causes
Faulty oven temperature sensor (RTD probe)
The RTD probe resistance drifts out of specification and reports an erroneously high temperature to the control board, triggering a false over-temp shutdown.
DIY PossibleStuck relay on electronic control board
A welded bake or broil relay contact on the board keeps the heating element continuously energized, causing genuine over-temperature in the cavity.
Requires ProfessionalDefective electronic control board
Internal firmware or component failure on the board causes it to misinterpret sensor data or lose proper control of element switching.
Requires ProfessionalSafe Checks You Can Do
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1
Turn off the oven and ventilate the kitchen
Press Cancel/Off immediately, open a window or turn on the range hood fan, and allow the oven cavity to cool to room temperature (30–45 minutes) before inspecting.
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2
Test the RTD temperature sensor
Disconnect power at the breaker. Locate the RTD probe on the rear interior wall of the oven cavity. Unplug the two-wire harness connector and measure resistance with a multimeter. At room temperature (~70°F) a healthy LG RTD reads approximately 1,080 Ω. A significantly lower or higher reading indicates a defective sensor that should be replaced.
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3
Perform a hard reset and monitor
Restore power after 5 minutes, set the oven to 350°F, and use a separate oven thermometer to verify the actual cavity temperature matches the set point. If the oven heats accurately and F4 does not return, the event may have been transient. Monitor for recurrence.
When to Call a Professional
Contact a qualified technician if:
- RTD probe tests within specification (~1,080 Ω) but F4 still triggers — board relay or logic fault requires professional evaluation.
- Oven cavity genuinely overheats (food scorching well before expected time) before shutdown — stuck relay on control board needs replacement.
- F4 triggers immediately on a cold oven after reset — sensor or board fault that persists regardless of actual temperature.
Need Professional Help?
Find qualified technicians in your area for proper diagnostics and repair.
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