An induction cooktop heats the pan directly by inducing current in its base, and to do that it must first detect a pan it can work with. When it cannot, an LG induction zone shows its power level flashing, or a pan symbol, and stays cold. Owners read that as a fault. Nearly always it is the cooktop being particular about what is on it, and the reasons are worth knowing before anyone is called.
The Magnet Test
Induction needs a base with iron in it. Cast iron, enamelled steel and most stainless steel pans work; aluminium, copper and glass do not, and some stainless pans with an aluminium sandwich base are not magnetic enough. Hold a refrigerator magnet to the bottom of the pan. If it grips firmly the pan can be detected; if it slides off or barely holds, the cooktop is right to ignore it. Pans marketed as induction-ready sometimes have a thin steel disc that works on high settings and drops out on low.
Size and Position
Each zone has a minimum pan diameter, printed in the manual, and a pan smaller than that is not detected at all. A pan that is large enough but sitting off centre may be detected and then lost as it is moved. Set the pan flat in the middle of the zone. A warped base that rocks, or a pan with a deep concave bottom, keeps too much of its metal away from the glass and is detected intermittently. Bridged or flex zones have their own rules about where a griddle must sit, and the manual's diagram is the authority.
Sounds and Pulsing That Are Normal
A soft hum, a buzz that changes with the pan, and a clicking at low power are the nature of induction, not faults; at low settings the zone switches on and off rather than running continuously, and a light pan may tick as it does. The cooling fan running after the zone is off is normal. HS beside a zone means the glass is still hot, and LG states that this is an indication rather than an error code.
Power Sharing
Zones on LG induction cooktops are paired, and the pair shares a maximum output. Running two pans on boost at once, or one on boost and its partner on high, causes the cooktop to reduce one of them, which looks like a zone that will not hold its setting. That is a design limit, described in the manual.
The Owner Reset
If a zone that detected a pan yesterday will not detect it today, or the controls stop responding, switch the cooktop off at its breaker, leave it off for a few minutes and turn it back on. Induction cooktops are hard-wired, so the breaker is the only way to remove power. Then dry the glass completely, because water or a metal object across the touch controls can lock them and on some models produces a code.
When It Is the Cooktop
A zone that detects nothing, including a cast-iron pan that the other zones accept, has a coil, sensor or board fault. A cracked glass top, however small the crack, means the cooktop should be turned off at its breaker and left alone until it is looked at, because the crack sits above live electronics and liquid will find it. Both are technician work behind the glass with the power off. Book an LG cooktop repair with the model number from the plate on the underside or the installation paperwork, which zone is affected, and which pans you tested.