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

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.

Find this part on Amazon →

As an Amazon Associate we earn from qualifying purchases.

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
    Amazon →

More LG microwave codes

DOOR DOOR / Door Error — Door switch / interlock fault F-1 F-1 — Main Control Board Fault F-2 F-2 — Thermistor / Temperature Out of Range F-3 F-3 — Key short / specific button stuck F-4 F-4 — Humidity / steam sensor fault F-5 F-5 — Damper Switch Error

All LG codes → All microwave codes →

Frequently asked questions

What does the F19 code mean on a LG microwave?

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.

What causes the F19 code on a LG microwave?

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.

Is it safe to keep using a LG microwave with a F19 error?

Limited use only. This is rated a serious-severity fault.

How do I fix F19 on a LG microwave?

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.

Always unplug an appliance before servicing it. This guide is for informational purposes and is not a substitute for a qualified technician.