LG [F13] fault codewhat it means and how to fix it

LG’s entry here is titled "F13/F14/F15 Error Codes" and its body says only that "F13 indicates a voltage error". Two of the three codes it is supposed to cover get no explanation at all, and there is nowhere else in LG’s microwave documentation that they appear. So this page publishes what LG published: F13 is a voltage error, F14 and F15 are codes LG name and do not define. Saying that plainly is more useful than filling the gap from a repair forum, and it also tells you something about what to expect from a phone call — quoting F14 to LG will get you an inspection, not a meaning.

As for the voltage error itself, the interesting thing is which voltage. A microwave contains several: incoming mains at 230 V, a low-voltage rail for the logic, and on the far side of the transformer or inverter a few thousand volts feeding the magnetron. A code that says only "voltage" does not tell you which one is out of specification, and both ends are plausible.

Supply problems are real and more common than people expect — a microwave is one of the heaviest single loads in a domestic kitchen, and on a long or heavily loaded circuit the voltage at the socket sags when it starts. Extension leads and multi-way adaptors make that worse, which is why an appliance that faults on one socket and behaves on another is telling you something about the installation rather than about itself. Internal supply faults are equally possible and are behind the cover. The one thing worth doing first is therefore the one thing that is free: plug it into a different circuit and see whether the code follows it.

1. 1

   Unplug it and plug it back in once. LG ask for that on every F code, and a genuinely one-off event will not return.

2. 2

   Take out anything between the appliance and the wall. No extension leads, no multi-way adaptors, no timer plugs — a microwave should be in a socket of its own.

3. 3

   Try it in a socket on a different circuit, ideally in a different room, and run a mug of water for a minute.

4. 4

   Note whether the code follows the appliance or stays with the socket. That single observation is the most useful thing you can hand an engineer or an electrician.

5. 5

   If the fault stays with one socket, the appliance is probably fine and the circuit needs looking at. If it follows the appliance, book a repair.

   Nothing here involves opening the appliance. The high-voltage capacitor inside stays charged after the plug is out, so the cover stays on whatever the code turns out to be.