LG MVEL2125 (MVEL2125F / D) 2.1 cu ft over-the-range microwave with ExtendaVent 2.0: quick sheet

Covers: LG MVEL2125F (PrintProof stainless) and MVEL2125D (PrintProof black stainless) 30-inch over-the-range microwaves with EasyClean interior, sensor cook, ExtendaVent 2.0 and Wi-Fi/ThinQ. LG and retailers list the F version as discontinued, with MVEL2125X named by LG as the newer model (check its own parts list).

Single sourceBrands: LG8 components

Mid-range LG OTR: 2.1 cu ft, 1,050 W output, 400 CFM, LED lighting, hidden vent and humidity-sensor cooking. Before quoting HV parts, open the case and check whether it uses an iron-core transformer or an inverter board; the fault logic below covers both, but parts and tests differ. LG's microwave codes F3 (key short) and F4 (humidity sensor) apply.

Safety first

Microwave high voltage (transformer or inverter board) can be lethal: unplug and discharge before touching internal parts. All internal HV work is caution.
Never operate with the case off or with a damaged door or seal.
Breaker off and two people for wall removal.

How it works

Start energizes the high-voltage section that drives the magnetron; the turntable and cavity fan run with it. Door interlock switches must all read correctly or it won't heat (and a failed switch can blow the line fuse).

The vent fan pulls cooktop air through the grease filters; ExtendaVent 2.0 is a pull-out vent extension that covers more of the cooktop.

Sensor cook uses a humidity sensor; a failed sensor shows F4 and sensor cycles stop early or never finish.

ThinQ adds app control and scan-to-cook; it does not change the basic heating circuit.

Components & tests

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

LG US microwave error codes help library

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Over-the-range microwave mounted above a stainless electric range by Curtis Adams, Pexels License

Diagnostic guides for this appliance

Guide · Microwave

Over-the-range microwave vent fan turns on by itself or won't turn off

Most OTR microwaves have a heat-protection thermostat that starts the vent fan when the cooktop below heats the unit, and on that cycle the fan cannot be switched off until the area cools. Some models also run the fan during and after microwave cooking or link the hood to the cooktop. If the fan runs in a cool kitchen, right at power-up, or for hours, suspect a thermostat stuck closed, a welded fan relay on the control board, a stuck vent key or a shorted wire.

8 steps ~45 minmoderate

Guide · Microwave

Microwave keypad locked or in demo mode (keys dead, or runs but doesn't heat)

Two software modes cause many no-fault calls: control/child lock and demo (showroom) mode, which runs everything except the magnetron. Clear them with the model's key sequence before any high-voltage diagnosis.

6 steps ~10 mineasy

Guide · Microwave

Known issue: Whirlpool WMH53520 / WMH73521 over-the-range microwave internal arcing (2016 recall)

In August 2016 Whirlpool recalled about 15,200 Whirlpool microwave hood combinations, models WMH53520 and WMH73521 (CS, CW, CB, CE, CH) with serial numbers TR33500000 to TR34899999, sold January 2014 to April 2016. Internal arcing during use can ignite an internal plastic part. The published remedy was a free replacement microwave. Units of this age are still installed in many homes and rentals.

6 steps ~20 mineasy

Other microwaves manuals

Manual · Microwave

LG LMV2031 / LMV1831 / LMVM2033 over-the-range microwave: quick sheet

LG 30-inch over-the-range microwaves LMV2031 (2.0 cu. ft., suffixes such as ST, SS, SB, SW, BD), LMV1831 (1.8 cu. ft., ST, SS, BD) and LMVM2033 (2.0 cu. ft., stainless). Transformer-type (non-inverter) units with a hidden vent grille, glass touch controls and a turntable, sold roughly 2015-2022; most are now listed as discontinued. LMHM2237 (2.2 cu. ft., taller cabinet, ExtendaVent 2.0) is a different, larger chassis: the fault logic below still applies, but check its own parts list before ordering anything.

10 components7 common failuresLG

Manual · Microwave

Frigidaire FFMV1846V / FFMV1645T / Gallery FGMV176NTF / FGMV17WNVF over-the-range microwave: quick sheet

Frigidaire 30-inch over-the-range microwaves: FFMV1846V (1.8 cu. ft., suffixes VS, VW, VB, VD), FFMV1645T (1.6 cu. ft., TS, TW, TB, TD, TM), Frigidaire Gallery FGMV176NTF (1.7 cu. ft.) and FGMV17WNVF (1.7 cu. ft.). Transformer-type units with a bottom grease filter, 2-speed vent and a turntable, sold roughly 2014-2021 and now discontinued (FMOS-series replacements). Factory revisions are shown by the last letter of the serial model (for example FFMV1846VSA/VSB); parts differ between revisions, so always order by the full model number.

10 components7 common failuresFrigidaire

Manual · Microwave

Galanz countertop microwaves (compact and retro, 0.7-1.2 cu ft): quick sheet

Galanz-branded countertop transformer microwaves sold at big-box retailers (e.g. GLCMKA07 retro 0.7 cu ft, 700 W; 1.1-1.2 cu ft models). Galanz also builds microwaves sold under other brand names; check the rating plate.

7 components5 common failuresGalanz