How to Fix LG Microwave Error F3

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⚠️ Safety Warning: Appliance repair involves electricity, gas, and moving parts. Always disconnect power before working on any appliance.

Error Code: F3 Difficulty: Moderate

Problem: There is a control panel malfunction or a key error. It can also indicate a temperature sensor error.

⚖️ Repair Decision

⚠️ CHECK WARRANTY / AGE

$100 – $250 Range

How to Fix F3 Error (Step-by-Step)

Unplug the microwave from the wall outlet to ensure your safety.
Open the microwave door and look for screws along the frame that hold the control panel assembly in place.
After removing the screws, gently pry the control panel assembly away from the microwave body.
Be careful not to pull too hard, as it is connected by a delicate ribbon cable to the main board.
Release the clip on the connector and detach the ribbon cable from the old keypad controller.
Replace the old keypad assembly with the new one (part ACM74119046 or ACM74119039).
Reconnect the ribbon cable, snap the control panel back into position, replace the screws, and test functionality.
Turn the appliance off, wait about 2 minutes, then turn it back on.

Next Steps and Parts

Recommended Parts to Check

Compatibility note: Exact LG microwave part numbers vary by complete model number, production revision, and internal layout. Treat these as diagnostic part-category searches, then confirm fit with the full model number before ordering.

Start here

LG microwave control panel

Common replacement category: Control panel or keypad

Symptom match: Most likely when: error F3 appears with unresponsive, stuck, or random button behavior.

Check first: Check first: stuck keys, moisture, ribbon cable seating, and keypad response.

Find compatible LG microwave control panel
Also check

LG microwave door switch

Common replacement category: Door switch

Symptom match: Most likely when: error F3 appears with start/stop or door-related interruptions.

Check first: Check first: latch alignment and switch continuity with power disconnected.

Find compatible LG microwave door switch
Harness path

LG microwave wire harness

Common replacement category: Control harness

Symptom match: Most likely when: error F3 is intermittent or changes after the panel is moved.

Check first: Check first: loose ribbon connectors and damaged harness insulation.

Find compatible LG microwave wire harness
Control path

LG microwave control board

Common replacement category: Electronic control board

Symptom match: Most likely when: keypad, door, and harness checks pass but error F3 returns.

Check first: Check first: visible board damage and model-matched diagnostics.

Find compatible LG microwave control board

Model-number note: Use the LG microwave model tag before buying; these links are not universal fit claims.

LG Microwave Error F3 Checks Before Replacing Parts

Disconnect power before opening the cabinet, and do not touch high-voltage parts unless you are trained to discharge and test them safely.
Confirm the full LG model number from the tag before matching any replacement category to the appliance.
Check the simple symptom path first: door closure, keypad response, airflow, and any obvious loose or damaged connectors.
Test switches, sensors, or harnesses with a meter where the service data supports it instead of ordering parts by code alone.
If the related parts test correctly, inspect the control area and harness before considering a model-matched control board.

When It’s Better to Replace Than Repair

Microwave repairs require extra caution because high-voltage parts can retain a dangerous charge after unplugging.
Door switches, turntable motors, fuses, and controls may be replaceable, but many microwave failures are safer and cheaper to solve with replacement.
For repair parts or built-in trim kits, verify exact fit with the full microwave model number before buying; these links are general replacement-appliance shopping options.