LG Range F4 Error: Oven over-temperature protection triggered
LG range error — here’s what you need to know. The F4 error code on your LG range indicates oven over-temperature — the cavity has exceeded 650°F for more than 2 minutes during normal cooking. This is a High severity issue. What Does F4 Mean on an LG Range? F4 is LG’s oven over-temperature protection […]
~55%
DIY Fixable
From $80 (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 until the root cause is confirmed. An over-temperature condition during cooking is a fire hazard. Confirm the RTD sensor and control board are functioning correctly before resuming use.
Can I reset the code?
Yes. A power reset (disconnect at breaker for 5 minutes) will clear the F4 code, but the code will return if the underlying hardware fault is not repaired. Do not rely on a reset as a permanent fix.
When to stop immediately?
Stop if you notice: Stop using the oven immediately when F4 appears — continued operation risks a kitchen fire., Stop if you notice smoke coming from the oven cavity during a normal cooking cycle..
Symptoms You May Notice
Food burns or scorches faster than expected at normal temperature settings
Food in the oven chars or burns significantly sooner than the recipe requires, indicating actual cavity temperature is much higher than the dial or display setting.
F4 code on display with oven shut down
The control panel displays F4 and the bake or broil element cuts off entirely, leaving the oven non-functional until the fault is addressed.
Strong burning smell from oven cavity
An acrid or metallic burning odor emanates from the oven interior as temperatures climb beyond the safe cooking threshold.
Oven runs continuously without cycling off
In a relay-stuck-on scenario, the bake element stays energized without the normal on-off cycling that maintains set temperature, causing runaway heat.
Possible Causes
Shorted or drifted oven temperature sensor (RTD)
The RTD probe resistance drops out of specification, sending a falsely elevated temperature reading to the control board and triggering the over-temp cutoff.
DIY PossibleStuck bake or broil relay on control board
A welded relay contact keeps the heating element energized continuously, genuinely driving cavity temperature past 650°F.
Requires ProfessionalFaulty electronic control board
Internal board logic errors or failed components can cause the board to misinterpret sensor data or lose control of element power cycling.
Requires ProfessionalSafe Checks You Can Do
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1
Turn off the range and allow it to cool completely
Switch the oven off, open a window for ventilation, and allow the cavity to cool to room temperature (at least 30–45 minutes) before inspecting any components.
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2
Inspect and test the oven temperature sensor
After the oven cools, disconnect power at the breaker. Locate the RTD probe inside the oven cavity (typically rear upper-left wall). Disconnect its harness and measure resistance with a multimeter — it should read approximately 1,080 Ω at 70°F. A reading significantly outside this range indicates a faulty sensor.
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3
Perform a hard reset
Disconnect power at the wall or breaker for 5 minutes, then restore. If F4 does not return during a short test cycle and food cooks at accurate temperatures, the event may have been transient. Monitor closely.
When to Call a Professional
Contact a qualified technician if:
- RTD resistance tests within specification but F4 still triggers — control board relay or logic fault requires professional diagnosis.
- Oven genuinely reaches very high temperatures (burning food quickly) before cutoff — stuck relay on board needs replacement.
- F4 code returns within minutes of reset on a cool oven — intermittent board fault requiring technician inspection.
Need Professional Help?
Find qualified technicians in your area for proper diagnostics and repair.
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