What does LG Microwave F17 Error Code - Causes & Fix mean?

F17 means a temperature sensor fault in your LG microwave. Most often the sensor or its wiring has failed and requires service.

How do I fix LG Microwave F17 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 F17 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 Microwave F17 Error Code - Causes & Fix?

The most frequently replaced parts for LG Microwave F17 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 Microwave F17 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 Microwave F17 Error Code - Causes & Fix

LG Microwave F17 Error Code — What It Means

The F17 error code on LG microwaves indicates a problem with the temperature sensor circuit. On standard models, LG defines F17 as a general temperature sensor fault. On some NeoChef models, the code is listed as F-17 and specifically refers to the inverter temperature sensor. Either way, the fault points to a problem in the sensing circuit that monitors the microwave’s internal heating or inverter temperature, not a user-setting issue. LG’s official guidance states that this error requires service.

The code typically appears when the control board cannot read a valid signal from the temperature sensor or thermistor. This happens when the sensor itself has failed, the wiring harness is damaged or disconnected, or the inverter assembly (on models with an inverter sensor) has developed a fault. A temporary control glitch can also trigger the code, though if it returns after a power reset, the underlying hardware issue needs professional attention.

Jump to Fix

Common Causes

Failed temperature sensor or thermistor The sensor has shorted, opened, or drifted out of specification and no longer sends valid readings to the control board.
Loose, damaged, or open wiring harness The connector at the sensor, inverter, or control board has come loose, or the wires have been damaged by heat or vibration.
Inverter temperature sensor circuit fault On NeoChef and similar models, the inverter’s dedicated temperature sensor or its circuit has failed and cannot protect the inverter from overheating.
Faulty inverter assembly The inverter board itself has developed a fault that prevents the temperature sensor circuit from operating correctly.
Control board issue The main control board has a defective input circuit or processing fault that misreads or cannot process the sensor signal.
Temporary control glitch A power surge or electronic hiccup has triggered the code once, but the hardware is still intact and will clear after a reset.

Step-by-Step Fix

Unplug the microwave and wait at least one minute to reset the control board, then plug it back in and run a test cycle to see if the F17 code clears.
Note your exact model number from the rating label (usually inside the door or on the back) and locate the service manual or wiring diagram for that model before opening the unit.
Discharge the high-voltage capacitor using an insulated screwdriver across its terminals, then remove the outer cabinet to access the sensor and inverter area.
Inspect the temperature sensor and its wiring harness for visible damage, corrosion, or loose connectors, and reseat all connectors firmly.
Test the sensor electrically using a multimeter set to resistance mode, comparing the reading to the specification in your service manual (if the sensor is open or shorted, replace it).
Check the inverter assembly and control board connections if the sensor tests good, looking for burnt components, loose wiring, or signs of overheating on the inverter board.
Reassemble and test after any repair, running the microwave for several minutes to confirm the F17 code does not return and the unit heats normally.

Parts Often Needed

Part	Notes
Temperature sensor / thermistor	Amazon \| Match the part number to your exact LG model. The sensor is usually a two-wire thermistor mounted near the magnetron or inverter.
Inverter assembly	Amazon \| Required on NeoChef and inverter-driven models if the inverter temperature sensor circuit is integrated into the board and cannot be replaced separately.
Main control board	Amazon \| Order only if the sensor and inverter both test good but the F17 code persists. Verify the board part number before purchasing.
Wiring harness	Amazon \| Needed if the connector or wire insulation is damaged. LG typically sells harnesses as model-specific sub-assemblies.

When to Call a Pro

LG’s official guidance for F17 is to request service rather than attempt a DIY repair. Microwaves store lethal high voltage in the capacitor even when unplugged, and working inside requires proper discharge procedures and insulated tools. If you are not comfortable discharging the capacitor, reading a wiring diagram, or using a multimeter to test sensor resistance, call a qualified appliance technician. Also call a pro if the code returns after a power reset, if you cannot locate the exact sensor for your model, or if replacing the sensor does not clear the fault (indicating an inverter or control board issue). Most in-home microwave repairs cost less than replacement, especially on higher-end LG models, so professional diagnosis is often the most cost-effective path.