--- title: "Microwave starts when the door closes" description: "LG microwave starts when the door closes — stop using it and unplug it. This is a failed door interlock, and it means the switch that is supposed to prove…" url: "https://lgmiami.support/symptoms/microwave-turns-on-by-itself/" date_modified: "2026-09-05" Appliance type: "Microwaves" --- # LG microwave starts when the door closes ### Unplug it, and do not use it meanwhile There is no version of this that is safe to live with. A microwave is designed so that three separate switches must agree the door is closed before the magnetron can run; when one sticks, the safety chain that stops microwaves being produced with the door open is compromised. Take the plug out. If it is hardwired or over the range, switch its breaker off. ### What it usually means, by the kind of LG appliance LG sells one appliance in several forms — five shapes of washer, three kinds of dryer, four fuels of range — and the same behavior points at different things on each of them. A built-in side-by-side and an integrated column are not the same service situation, and a dual-fuel range and an induction range fail in different halves. - **Over the range** — The interlocks sit in the door frame behind the fascia. It is a contained repair. - **Countertop** — Same switches, same job, and worth repairing even on a machine you might otherwise replace — an unplugged machine is not usable either way. - **Combination wall oven** — The interlock arrangement is the same. The access is through the front trim. ### Why three switches A microwave door has an interlock system rather than a single switch, and the design is deliberately unforgiving: two switches must confirm the door is closed before the machine can run, and a third — a monitor switch — is wired to blow the fuse outright if the others disagree. That arrangement exists precisely because the consequence of getting it wrong is a machine producing microwaves into a room. A machine that starts by itself has lost part of that chain. ### What the repair involves The switches sit in the door frame behind the front fascia. Replacing them is a short job for someone with the right part and the right respect for the capacitor, and the machine is tested afterwards to confirm the whole interlock chain behaves as it should — not just that the symptom has gone away. A stuck door interlock switch The cause in nearly every case. Small, cheap, and it is what the safety design depends on. A worn or misaligned door latch The hooks on the door edge wear, and the switches then read the wrong state. A control board that has failed closed Less common and it is diagnosed after the switches are ruled out. Unplug it or switch off its breaker Before anything else, and before you finish reading this page. Look at the latch hooks on the door edge They should be square and undamaged. A bent one is often visible. Do not open the case to look further The capacitor holds a dangerous charge. This is the appliance to leave to a technician. Book it as a safety repair Say what it is doing when you call. It changes how we schedule it. It runs as soon as the door shuts What it usually means Unplug it now — this is the one microwave symptom that is not a wait-and-see The interlock is a small cheap switch and the repair is short It is safe to use again once the switch is replaced and tested Unplug it, and do not use it meanwhile There is no version of this that is safe to live with. A microwave is designed so that three separate switches must agree the door is closed before the magnetron can run; when one sticks, the safety chain that stops microwaves being produced with the door open is compromised. Take the plug out. If it is hardwired or over the range, switch its breaker off. What it usually means, by the kind of LG appliance LG sells one appliance in several forms — five shapes of washer, three kinds of dryer, four fuels of range — and the same behavior points at different things on each of them. A built-in side-by-side and an integrated column are not the same service situation, and a dual-fuel range and an induction range fail in different halves. Over the range — The interlocks sit in the door frame behind the fascia. It is a contained repair. Countertop — Same switches, same job, and worth repairing even on a machine you might otherwise replace — an unplugged machine is not usable either way. Combination wall oven — The interlock arrangement is the same. The access is through the front trim. Why three switches A microwave door has an interlock system rather than a single switch, and the design is deliberately unforgiving: two switches must confirm the door is closed before the machine can run, and a third — a monitor switch — is wired to blow the fuse outright if the others disagree. That arrangement exists precisely because the consequence of getting it wrong is a machine producing microwaves into a room. A machine that starts by itself has lost part of that chain. What the repair involves The switches sit in the door frame behind the front fascia. Replacing them is a short job for someone with the right part and the right respect for the capacitor, and the machine is tested afterwards to confirm the whole interlock chain behaves as it should — not just that the symptom has gone away. ### It only does it sometimes. That is the same problem and it is arguably worse, because an intermittent interlock is one that will pass a casual test. Treat it exactly the same way: unplug it and have it looked at. ### Is my kitchen contaminated? No. Microwaves are not radioactive and nothing lingers — the energy exists only while the magnetron is powered and it stops the instant it is not. The risk is exposure while it is running with the door open, which is why the machine comes out of service now rather than later. --- **[Read full article: Microwave starts when the door closes](https://lgmiami.support/symptoms/microwave-turns-on-by-itself/)**