How an LG range reports a fault
An LG range watches its oven cavity through an RTD temperature sensor (about 1080–1100 Ω at room temperature) and runs everything through an electronic control, so when something is wrong it flashes an F-code on the display. Reading that code is the quickest way to an accurate LG range repair, because each one points at the sensor, the control board, the keypad or the door lock. LG ranges come in gas, electric, dual-fuel and induction, so the cooktop varies while the oven F-codes follow the same logic.
The F-series codes
F1 is an upper-oven thermistor open or short, and F4 the lower-oven thermistor. F2 is the serious one — a runaway high-temperature condition; turn the breaker off. F3 is a shorted keypad key held over a minute, F6 an overheat or stuck relay, F7 the convection fan, and F9 an oven that will not heat (element, igniter or thermal fuse). F10 and F20 are upper and lower door-lock faults, and F11 is a comms fault between the main and display boards. The general fix is to clear or turn off, trip the breaker for thirty to sixty seconds, then service if it returns.
Display words that are not faults
Several messages are status, not stored codes. H5 is the hot-surface indicator, PF is a power failure, 5b is Sabbath mode, CL is Clean-Lock, and LOC is the child or control lock. These do not need service.
What to check, and when to call
A keypad lockout or a one-off PF usually clears with a breaker cycle. A persistent F1/F4 sensor code, an F2 runaway, an F9 no-heat condition or an F10/F20 latch fault that strands the door locked needs an experienced technician with genuine parts. See the oven F-codes guide and the F9 not-heating guide, browse the error codes library, then book range repair. Confirm your model on the manufacturer’s site at lg.com/us.