LG Range F3 and F5 Error Codes — Temperature Sensor and Locking Motor Fix

If your LG range just lit up with an F3 or F5 error code on the display, you are probably staring at a cold oven wondering what broke and how much this is going to cost. The good news: both codes point to specific, fixable problems you can usually handle yourself without calling a technician. F3 means your oven temperature sensor has failed open or shorted. F5 means the door lock motor has stopped working, which keeps the self-clean cycle from running.

Let us walk through the fixes for each code, starting with the simplest step that sometimes solves both.

Quick Reference

Fix 1: Power Cycle the Range

Before you buy any parts, unplug the range or flip the breaker off for a full five minutes. This clears the control board’s memory and resets the error state. About 10% of the time, a transient voltage glitch triggers F3 or F5, and a simple power cycle wipes it out.

Plug the range back in and check the display. If the code is gone, run a test cycle — heat the oven to 350°F for 10 minutes — to make sure the error does not return. If it does come back, move to the next fix.

Fix 2: Test the Oven Temperature Sensor (F3 Only)

The F3 code means the control board cannot read the oven temperature sensor, also called an RTD (resistance temperature detector). This is a small probe inside the oven cavity that changes resistance as the temperature changes. When it shorts or opens, the board has no way to regulate heat.

You will need a digital multimeter to test it. Any basic model works — here is one we recommend:

Digital Multimeter — Klein Tools MM400

Step-by-step:

1. Unplug the range or shut off the breaker.
2. Open the oven door and remove the racks to access the sensor. It is usually mounted on the back wall of the oven cavity, held in by one or two screws.
3. Remove the screws and gently pull the sensor probe out of the oven. Do not yank the wire — follow it to the connector behind the rear access panel.
4. Remove the rear access panel (usually 4-6 screws on the back of the range).
5. Unplug the sensor connector from the main wiring harness.
6. Set your multimeter to ohms (Ω). Touch the probes to the two sensor terminals.
7. At room temperature (about 70°F), a good sensor reads approximately 1080-1100 ohms. A bad sensor reads 0 ohms (short) or infinite ohms (open).
8. If the reading is out of range, replace the sensor.

Fix 3: Replace the Oven Temperature Sensor

If the sensor failed the resistance test, replacement is straightforward.

Oven Temperature Sensor Replacement — Compatible with Most LG Ranges

1. Order a replacement RTD sensor compatible with your LG model number.
2. Unplug the range.
3. Remove the old sensor from the oven cavity wall and disconnect the wire harness from the rear.
4. Install the new sensor — route the wire connector through the rear panel, plug it into the harness, and secure the probe in the oven cavity with the original screws.
5. Replace the rear access panel.
6. Plug the range back in. If the F3 code is gone, the fix worked.
7. Calibrate if needed: some LG ranges require you to enter calibration mode after sensor replacement. Check your manual, but most modern models auto-detect the new sensor.

If the F3 code returns within a week, inspect the wire harness for damage. A chafed or pinched wire can cause intermittent sensor readings:

Universal Wire Harness Connector Kit

Fix 4: Check the Door Lock Mechanism (F5 Only)

The F5 error appears when the range cannot engage the door lock during a self-clean cycle. The lock mechanism has two parts: a small DC motor and a plastic latch that slides into place.

Visual inspection first:

1. Unplug the range.
2. Open the oven door and look at the top edge where the latch lives. On most LG ranges, it is a visible white or black plastic piece near the control panel.
3. Manually attempt to slide the latch. It should move freely. If it is stuck or grinding, the mechanism is jammed.
4. Check for debris, grease buildup, or melted plastic around the latch area.

Electrical test:

1. Remove the rear access panel.
2. Locate the door lock motor on the back of the control panel area. It is a small black or white box with a multi-pin connector.
3. Unplug the connector and test the motor windings with your multimeter set to ohms. A good door lock motor typically reads between 1,000 and 5,000 ohms across the motor terminals.
4. If you get an open reading (infinite ohms), the motor is burned out.

Fix 5: Replace the Door Lock Motor Assembly

If the door lock motor is dead, you need to replace the entire assembly. The motor, latch, and microswitch usually come as one unit.

LG Range Door Lock Motor Assembly — OEM or Compatible

Step-by-step replacement:

1. Unplug the range.
2. Remove the rear access panel.
3. Disconnect the wire harness from the old lock assembly.
4. Remove the mounting screws — usually two to four — holding the assembly to the range frame.
5. From the front of the range, reach up and pull the latch through its slot. The whole assembly slides out.
6. Install the new assembly in reverse order: latch first through the front slot, align the mounting holes, secure with screws, plug in the harness.
7. Test by hand: the latch should slide smoothly. Plug in the range and run a short self-clean cycle to verify the F5 code clears.

When to Call a Professional

If you have tested the sensor and lock motor, confirmed they are good, and the error codes keep returning, the problem may be the main electronic control board. Control board replacement requires soldering or board-level diagnosis and is usually best left to a licensed appliance technician. The cost of a service call (typically $150-250) is often worth it compared to the risk of damaging a $400 control board.

Parts Summary

• Digital Multimeter — Klein Tools MM400 — for testing sensor and motor resistance
• Oven Temperature Sensor (RTD) — direct replacement for most LG ranges
• Wire Harness Connector Kit — if the original harness is damaged
• Door Lock Motor Assembly — complete replacement unit with motor, latch, and switch
• Klein Tools Wire Stripper and Cutter — for harness repair work

Related Guides

• LG Range F3 Error Code — Complete Guide
• LG Range F9 Error Code and Complete Troubleshooting Guide
• All LG Range Error Codes by Brand