How an LG microwave reports a fault
LG microwaves — over-the-range LMV and MVEL units and countertop NeoChef LMC models — carry a genuine set of F-codes centred on the mainboard, the sensors and the inverter, alongside observable symptoms for the parts that do not self-report. Reading the code is the start of any LG microwave repair, and it usually tells you whether the issue is a simple reset or a service call.
The codes you will see
F1 points at the mainboard, F2 at a thermistor or temperature fault, F3 at the keypad (clean it first), and F4 at the humidity sensor. F10/E10 is a stuck key, often cleared by unplugging the unit for a minute. F11 is an inverter comms fault, and F13/F14/F15 are inverter over-current or voltage faults. LOC is child lock, DOOR means the door is not latched, and 12H/24H are clock-format settings — none of these are faults.
Symptoms with no code
Some of the most common microwave problems do not throw a code. A microwave that runs but does not heat points at the magnetron, the high-voltage diode or the capacitor; sparking or arcing points at a damaged waveguide cover or burnt residue; a turntable that will not turn points at the drive motor or coupler; a door that will not open points at the latch; and on an over-the-range unit, the vent fan or light may fail independently. These are read from behaviour, not the display.
What to check, and when to call
For a stuck key, unplug the unit for a minute; for sparking, clean the cavity and check the waveguide cover. Because a microwave stores high voltage in its capacitor even when unplugged, no-heat, sparking and inverter faults should always go to an experienced technician rather than DIY. See the guides on a microwave not heating, sparking or arcing and a turntable not turning, browse the error codes library, then book microwave repair. Confirm your model on the manufacturer’s site at lg.com/us.