LG · Microwave Serious

F19 — Inverter / High-Voltage Fault

Per LG's official microwave error-code list, F19 means 'a heating issue was detected' and requires service — LG's own consumer page does not specify inverter DC-voltage protection or any other exact circuit. The inverter-related detail below matches LG service literature but goes beyond what LG states publicly; treat it as the likely area to check, not a confirmed diagnosis.

Keep using it?
Limited use only
DIY difficulty
Hard
Typical cost
$30-70
Verified against
lg.com ↗

The fix

Humidity sensor

Microwave humidity / steam sensor fault

$30-70 moderate difficulty 60 min Tools: screwdriver, nut driver

Diagnose first: Grease buildup or sensor failure trips humidity-based auto-cook modes; clean the vent area before replacing.

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How to fix it

  1. Unplug the microwave (or switch off the breaker) for 60 seconds, then retry — a transient fault may clear.
  2. If F19 returns, the inverter power board is the most likely failure. LG officially recommends professional service for this code.
  3. 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.
  4. 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.

Why it happens

Typical signs: F19 shown on the display · Microwave runs but does not heat properly

  • Most likely: Defective inverter power board The inverter board converts line voltage to high-voltage drive for the magnetron. LG states this error requires service to resolve.
  • Failed magnetron or inverter wiring A shorted magnetron or damaged harness between the inverter and magnetron can also produce a heating fault.

Other parts sometimes needed

If diagnosis points to a failed part, these are the common replacements. As an Amazon Associate we earn from qualifying purchases.

  • LG microwave inverter power board Common replacement
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More LG microwave codes

CH CH / Child Lock — Control locked DOOR DOOR / Door Error — Door switch / interlock fault F-1 F-1 — Main Control Board Fault F-2 F-2 — Keypad / touch panel shorted F-3 F-3 — Key short / specific button stuck F-4 F-4 — Humidity / steam sensor fault

All LG codes → All microwave codes →

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician. Verified against manufacturer documentation: lg.com.