F16 appears after several heating cycles
The microwave may work for a while, then throw the code after repeated use or longer cook times.
Start here: Start with cool-down time and airflow around the microwave before assuming a failed part.
Microwave not heating
LG Microwave F16 Error
Direct answer: An LG microwave F16 error usually means the oven thinks it is overheating or is getting a bad temperature-related signal. The first things to check are blocked vents, a hot cabinet from heavy use, and whether the error clears after a full power reset and cool-down.
Most likely: The most common real-world cause is heat buildup around the microwave from blocked airflow or back-to-back cooking, especially on over-the-range and built-in units.
Treat F16 like a heat warning until proven otherwise. If the microwave still runs but will not heat, or the code comes back right after reset, separate an airflow or recent-overheat issue from a door-latch problem first. Reality check: a lot of these codes show up after the microwave has been worked hard, not because a major part instantly failed. Common wrong move: unplugging it for ten seconds, seeing the display come back, and assuming the problem is fixed without testing a full heat cycle.
Don’t start with: Do not start by opening the cabinet or ordering internal electrical parts. Microwave high-voltage sections can hold a dangerous charge even when unplugged.
If the cabinet feels hotLet the microwave sit unplugged for 15 to 30 minutes, then retry with a cup of water.
If the code returns immediatelyStop at basic external checks and plan for service, because the likely fault is inside the microwave.
Last reviewed: 2026-04-17
What the F16 error usually looks like
F16 shows up right away after pressing Start
The display errors out almost immediately, sometimes before the food warms at all.
Start here: Check the door closing feel and latch area first, then do a full unplug reset.
F16 clears after unplugging but comes back
The microwave seems normal for one short test, then the code returns on the next real use.
Start here: Look for a repeatable heat buildup pattern and blocked venting around the cabinet.
Microwave runs but heating is weak or inconsistent
The light, fan, and turntable may run, but food stays cool or only partly warms before the code appears.
Start here: Treat that as a stop point for DIY beyond external checks, because internal components may be involved.
Most likely causes
1. Blocked or restricted microwave airflow
If vents are packed with grease, dust, or cabinet items are crowding the unit, heat cannot leave the microwave properly and the control may post an overheat-style code.
Quick check: Feel for heavy heat around the top or front vent area and inspect visible vent openings for grease or blockage.
2. Microwave was overheated by heavy recent use
Back-to-back cooking, long run times, or using the microwave right after the cooktop heated the cabinet can trip a heat-related fault even when no part has failed.
Quick check: Let the unit cool fully, then test one short one-minute water-heating cycle from a cold start.
3. Door latch or door-closed sensing issue
If the door does not close cleanly or the latch area is sticky, the microwave can misread operating conditions and stop with an error instead of heating normally.
Quick check: Open and close the door slowly and listen for a clean latch click without slop, rubbing, or bounce-back.
4. Internal temperature-sensing, cooling, or control fault
If F16 returns immediately after reset, with clear vents and a properly closing door, the problem is likely inside the microwave.
Quick check: After a full cool-down and reset, run one short test. If the code comes back right away, external causes are less likely.
Step-by-step fix
Step 1: Cool it down and reset it the right way
A quick unplug often does nothing if the microwave is still heat-soaked. Give it time to cool so you can tell the difference between a temporary overheat and a repeat fault.
- Cancel the cycle and unplug the microwave or switch off power at the outlet.
- Leave the door closed for a minute, then open it and let the cavity air out.
- Wait 15 to 30 minutes so the cabinet and controls can cool down.
- Plug it back in and set the clock if needed.
- Heat one microwave-safe cup of water for 60 seconds from a cold start.
Next move: If the microwave heats the water normally and no code appears, recent overheating is more likely than a hard part failure. If F16 returns immediately or during that short test, keep going with external checks only.
What to conclude: A microwave that recovers only after a real cool-down usually has an airflow or heat-load problem. One that errors again right away is more likely dealing with a door-sensing or internal fault.
Stop if:
- You smell burning plastic or electrical odor.
- The microwave trips a breaker or loses power completely.
- You see arcing, sparks, or smoke.
Step 2: Check the vents and the space around the microwave
Poor airflow is the most common homeowner-fixable cause on this kind of error, especially when grease and dust build up around vent openings.
- Inspect the visible vent openings on the front, top, or underside depending on the microwave style.
- Remove loose dust with a dry cloth or vacuum brush held gently at the vent opening.
- If there is greasy buildup on accessible exterior vent grilles, wipe with a cloth dampened with warm water and a little mild dish soap, then dry it.
- Make sure nothing stored around the microwave is blocking side, top, or front airflow.
- If this is an over-the-range microwave, check that the underside intake area is not packed with grease.
Next move: If the microwave now completes a short water-heating test without the code, airflow restriction was likely the trigger. If vents are clear and the code still returns, move to the door and latch check.
What to conclude: A microwave that improves after cleaning and clearing vents was likely running too hot. No change points away from simple airflow restriction.
Step 3: Check how the door closes and latches
A sloppy or sticky door can cause false operating faults, and this is one of the few microwave checks you can do safely from the outside.
- Open the door and inspect the latch area for food splatter, grease, or anything keeping the door from seating fully.
- Clean the door edge and latch opening with a soft cloth and mild soap solution, then dry it.
- Close the door slowly and watch for sagging, rubbing, or a bounce-back that keeps it from fully seating.
- Press gently on the closed door near the latch side and start a short test cycle with water.
- Notice whether the door feels loose, needs lifting, or changes behavior when you press on it.
Next move: If the microwave runs normally only when the door is pressed firmly closed, the latch or door-closed sensing area is the likely problem. If the door feels solid and the code still returns, the fault is probably not a simple closure issue.
Step 4: Look for a repeat heat pattern before you call it internal
You want one clean answer: does this happen only after the microwave gets warm, or does it happen every time no matter what? That tells you whether the problem is likely airflow-related or inside the unit.
- From a fully cooled state, heat one cup of water for 60 seconds and note whether it finishes normally.
- If it does, let the microwave rest for two minutes, then run a second 60-second water test.
- If both pass, try one slightly longer heating cycle and watch for when the code appears.
- Pay attention to whether the cabinet gets unusually hot, the fan sounds weak, or the error shows up only after repeated use.
Next move: If the microwave only fails after warming up, heat management inside or around the unit is the leading suspect. If it fails on the first short test from a cold start, an internal sensor, cooling fan, or control issue is more likely.
Step 5: Stop at the cabinet and choose the repair path
By this point you have ruled out the safe homeowner checks. Microwaves can store dangerous voltage, so the next move should be deliberate, not exploratory.
- If the code stayed gone after cool-down and vent cleaning, keep using the microwave normally but avoid long back-to-back cycles for a few days and watch for recurrence.
- If the door clearly has play, does not latch cleanly, or the microwave only behaves when the door is pressed, plan on a microwave door latch repair or professional door-switch diagnosis.
- If F16 returns from a cold start with clear vents and a solid-closing door, schedule appliance service or replace the microwave if repair cost is not sensible.
- When you call for service, report whether the code appears only after repeated use or also from a cold start, and whether pressing on the door changes anything.
A good result: If the microwave now heats water repeatedly without the code, you likely corrected an overheating condition rather than a failed major component.
If not: If the code persists, do not keep cycling power and testing it over and over.
What to conclude: Repeated F16 after the basic checks usually means an internal temperature-sensing, cooling, or control problem that is not a safe DIY cabinet-open repair.
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FAQ
What does F16 mean on an LG microwave?
In plain terms, F16 usually points to a heat-related fault or a bad temperature-related reading. That can be caused by poor airflow, recent overheating, a door-latch issue that confuses operation, or an internal sensing or control problem.
Can I keep using the microwave if the F16 code clears?
Only if it clears after a full cool-down and the microwave passes a short water-heating test without getting unusually hot or showing the code again. If F16 comes back, stop using it until the cause is sorted out.
Will unplugging the microwave fix F16?
Sometimes it clears a temporary overheat condition, but only if the microwave is given enough time to cool down. If the code returns right away or on the next short test, unplugging was just a reset, not a repair.
Is F16 caused by a bad door switch?
It can be related to the door-latch area, especially if the door feels loose or the microwave acts differently when you press on it. But on this page, door switches are not a safe guess-and-buy item. Start with door fit and latch feel from the outside.
Should I open the microwave to check the fan or sensor?
No. Once the diagnosis points inside the cabinet, this is a service job for most homeowners. Microwaves contain high-voltage parts that can stay dangerous after the unit is unplugged.