LG Microwave F19 — Microwave humidity / steam sensor fault
LG Microwave · Error code F19
What F19 Means
Inverter error — the control board detected a heating fault (inverter DC voltage protection error). The inverter power board is not delivering correct voltage to the magnetron, so the microwave may run but won't heat properly.
Most Likely Fix
Microwave humidity / steam sensor fault
Tools: screwdriver, nut driver
Diagnose first: Grease buildup or sensor failure trips humidity-based auto-cook modes; clean the vent area before replacing.
Find this part on Amazon →Symptoms
- F19 shown on the display
- Microwave humidity / steam sensor fault
Common Causes
The inverter board converts line voltage to high-voltage drive for the magnetron; when its DC voltage protection trips, the control flags F19. LG states this error requires service to resolve.
A shorted magnetron or damaged harness between the inverter and magnetron can pull the inverter output out of range and trip the same protection.
How to Fix It
- Unplug the microwave (or switch off the breaker) for 60 seconds, then retry — a transient fault may clear.
- If F19 returns, the inverter power board is the most likely failure. LG officially recommends professional service for this code.
- WARNING: The inverter circuit and high-voltage capacitor can hold a lethal charge even when unplugged. Do not open the cabinet unless you know how to safely discharge the capacitor.
- If you proceed DIY: unplug, discharge the HV capacitor, then test/replace the inverter board (typical part cost $80-150). If a new inverter still trips F19, suspect the magnetron.
Parts You May Need
If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.
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Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.