Microwave Diagnostics
LG Microwave
LG Microwave
Error Codes
Meanings, severity levels, safe checks you can perform, and when to call a technician.
Enter the code shown on your microwave display
Is it safe to keep using it?
Depends on code severity. Low/Medium codes often allow continued use, High severity requires immediate stop.
Can error codes be reset?
Some codes clear after power cycle. Persistent codes indicate underlying issues needing repair.
When should I stop using it?
Stop immediately for water leak codes, burning smell, or any High severity error.
Error Code Directory
Click any code for detailed troubleshooting steps
Low
Medium
High
Code
Meaning
Severity
Common Symptom
F-1
Open thermistor (temperature sensor failure)
Medium
The unit powers off during or at the start of a cooking cycle and displays F-1, refusing to run again until the error is addressed.
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F-2
Shorted thermistor (temperature sensor short circuit)
Medium
The microwave powers off within seconds of pressing Start, as the control board interprets the shorted sensor as an extreme overtemperature event.
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F-3
Shorted touchpad membrane (keypad fault)
Medium
Pressing buttons produces no response, random functions activate, or the microwave starts a cooking cycle without input — all signs that the keypad membrane is shorted.
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F-5
Humidity sensor fault (Auto Cook sensor failure)
Low
Sensor-based cooking modes (e.g., Auto Reheat, Sensor Cook) will not initiate or terminate the cycle early because the control board cannot get a valid humidity reading.
View
F-7
Stuck relay / welded contact (control board relay failure)
High
The most dangerous sign of a welded relay: the magnetron or interior light remains active even after the door is opened, because the stuck relay is bypassing the door interlock safety circuit.
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F-9
Over-temperature protection tripped (thermal shutdown)
High
The unit cuts power to the magnetron and displays F-9 during a cooking cycle; the top, sides, or rear panel are noticeably hotter than normal, indicating heat is not being dissipated properly.
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