This guide explains all LG Microwave error codes (CH series) with simple troubleshooting steps to help you identify and fix common issues safely before calling a technician.
F1
Keypad Error
- Check control panel for stuck or unresponsive buttons.
- Clean keypad surface from grease or moisture.
- Reset microwave power supply.
- Replace control panel if issue persists.
F3
Temperature Sensor Fault
- Inspect thermistor wiring connection.
- Check sensor alignment inside cavity.
- Allow microwave to cool down.
- Replace temperature sensor if faulty.
F4
Door Switch Error
- Ensure microwave door is fully closed.
- Check latch mechanism alignment.
- Inspect door switch operation.
- Replace door switch if defective.
F5
Magnetron Failure
- Unplug microwave immediately.
- Inspect high-voltage components (technician only).
- Check magnetron condition.
- Professional repair is required.
F6
Inverter Error
- Check inverter board connections.
- Inspect power supply stability.
- Reset microwave system.
- Replace inverter if needed.
SE
Sensor Error
- Check internal sensor wiring harness.
- Clean control board and cavity area.
- Restart microwave.
- Replace sensor if malfunctioning.
E11
Main PCB Failure
- Disconnect power for 10 minutes.
- Inspect PCB for burn or damage.
- Check wiring harness connections.
- Replace control board if needed.
E13
Touch Panel Communication Error
- Clean control panel surface.
- Check ribbon cable connection.
- Restart microwave system.
- Replace touch panel if faulty.
E14
Overheating Detected
- Allow microwave to cool completely.
- Check ventilation openings for blockage.
- Clean internal dust and grease buildup.
- Inspect cooling fan operation.
E15
Cooling Fan Malfunction
- Check fan for obstruction or debris.
- Inspect fan motor wiring connection.
- Clean internal dust buildup.
- Replace fan motor if not working.
F0
Control Board Communication Error
- Turn off and unplug microwave for 10 minutes.
- Inspect wiring between control board and display panel.
- Check connectors for moisture or dust.
- Replace main PCB if error persists.
F2
Humidity Sensor Error
- Clean interior sensor area inside cavity.
- Check sensor wiring connections.
- Restart microwave.
- Replace humidity sensor if faulty.
F7
Inverter Overcurrent Error
- Unplug microwave immediately.
- Inspect inverter board (technician only).
- Check magnetron condition.
- Professional repair required.
F8
Low Voltage Error
- Check household power supply stability.
- Avoid extension cords.
- Reset circuit breaker.
- Test microwave on a different outlet.
F9
High Voltage Transformer Fault
- Disconnect power immediately.
- Inspect high-voltage components (technician only).
- Check capacitor and diode condition.
- Professional repair required.
E10
Exhaust Fan Error
- Check ventilation fan for obstruction.
- Clean grease buildup inside unit.
- Inspect fan motor wiring.
- Replace fan if not functioning.
E12
Thermal Cutoff Activated
- Allow microwave to cool completely.
- Check ventilation and airflow paths.
- Clean internal dust and grease.
- Inspect thermal fuse if repeated.
E16
Relay Control Failure
- Unplug microwave and reset power.
- Inspect relay board connections.
- Check control PCB for damage.
- Replace relay board if necessary.
E17
Door Open Detection Fault
- Ensure door is fully closed.
- Inspect door latch and hooks.
- Check door switch alignment.
- Replace switch if defective.
E18
Sensor Calibration Error
- Reset microwave power.
- Clean sensor area inside cavity.
- Check sensor wiring connections.
- Replace sensor if calibration fails.
Frequently Asked Questions
Why is my LG microwave not heating?
This is usually caused by a faulty magnetron, inverter, or door switch. Professional inspection and repair may be required.
What does “SE” error mean on LG microwave?
SE indicates a sensor error. Reset the microwave and check sensor wiring connections or replace the sensor if faulty.
Why does my LG microwave show F3 error?
F3 means a temperature sensor fault. The thermistor may be damaged, disconnected, or giving incorrect readings.
Can I reset my LG microwave?
Yes. Unplug the microwave for 5–10 minutes, then plug it back in to reset the system and clear temporary errors.
Why does my LG microwave keep shutting off?
This may be caused by overheating protection, a faulty door switch, or unstable power supply. Allow the unit to cool before restarting.
Is it safe to use a microwave with an error code?
No. Stop using the microwave immediately if an error appears, especially those involving heating, sensors, or high-voltage components.
What causes sparking inside the microwave?
Sparking can be caused by metal objects, damaged waveguide cover, food residue buildup, or internal component failure.
Why is my LG microwave keypad not responding?
This may be due to moisture damage, stuck buttons, or a faulty control board. Cleaning or replacement may be required.
When should I call a technician for LG microwave issues?
Contact a qualified technician for magnetron failure, inverter faults, burning smell, electrical issues, or repeated error codes after resetting.
Important: Always unplug the LG microwave before inspection, cleaning, or troubleshooting. If the issue persists after basic checks, discontinue use and contact a qualified LG appliance technician for safe and proper repair.