What does LG Oven F4 Error Code - Causes & Fix mean?

F4 means the lower oven temperature sensor reads an open circuit. The most likely fix is replacing the lower oven thermistor.

How do I fix LG Oven F4 Error Code - Causes & Fix?

Follow the step-by-step diagnosis below. The most likely fix is identified by checking power, sensor resistance, and control-board signals in order — using a multimeter and the part numbers documented in the parts reference table.

Can I keep running the equipment with F4 active?

Generally no. Faults on Appliance units are emitted when a sensor, safety, or control circuit is outside its operating envelope. Running through an active fault risks compressor, heater, or control-board damage. Diagnose and clear the fault first.

What part is most commonly replaced for LG Oven F4 Error Code - Causes & Fix?

The most frequently replaced parts for LG Oven F4 Error Code - Causes & Fix are listed in the Parts Reference section of this guide with OEM part numbers and typical price ranges. Check the table for direct replacements.

Is LG Oven F4 Error Code - Causes & Fix a DIY repair or do I need a technician?

Sensor swaps, fan motor replacements, and condenser cleaning are typical DIY-level repairs. Anything involving refrigerant, gas, or high-voltage (>240V) work requires a licensed technician for both safety and code-compliance reasons.

LG Oven F4 Error Code - Causes & Fix

LG Oven F4 Error Code — What It Means

The F4 code is the lower oven version of a thermistor fault. The control board cannot read a valid temperature from the lower oven sensor, usually because of an open circuit in the sensor or its wiring.

This shows up on LG double ovens where the lower cavity has its own sensor. A working sensor reads near 1080 to 1100 ohms at room temperature.

Jump to Fix

Common Causes

Failed lower oven sensor The lower cavity thermistor has gone open and stopped responding to heat.
Broken sensor wiring A damaged wire run to the lower oven sensor interrupts the circuit.
Loose harness plug The connector between the lower sensor and the control board is not seated.
Sensor tip grounding out A bent probe touching the oven wall can short and trip the code.
Control board input failure Rarely the board channel that reads the lower sensor has failed.

Step-by-Step Fix

Press CLEAR/OFF and retry the lower oven to clear a one-time fault.
If F4 returns, cut power at the breaker for 30 seconds and restore it.
Remove the lower oven sensor mounting screws and pull the probe forward.
Disconnect the harness and test the sensor resistance with a multimeter.
Swap in a new sensor if the reading is zero, open, or far off 1080 to 1100 ohms.
Check the harness for damage and firmly reseat it at the main board.
Power up and bake briefly in the lower oven to verify the code is gone.

Parts Often Needed

Part	Notes
LG lower oven temperature sensor	Amazon \| Confirm it is the lower cavity probe for your double oven model.
Lower oven sensor harness	Amazon \| Replace only if you see scorching or broken wire strands.
Range main control board	Amazon \| Use only after the sensor tests good but the code persists.

When to Call a Pro

Bring in a technician if the lower sensor measures in range yet F4 keeps coming back, since that suggests a board level fault. Routing a new sensor wire through a built-in double oven is also a fair reason to call a pro.