Hob ring stuck on or red light stays on

What it usually means

Start by separating the light from the heat, because the searches that bring people here mix them up and the answers could not be more different. If a zone display shows an H, a small h, or a red indicator after you have switched the ring off, and the glass beneath it is hot, that is the residual heat indicator doing exactly what it is for. Every ceramic and induction hob sold in the UK has one, several manufacturers publish the threshold at which it goes out, and it is common for it to sit lit for twenty minutes after a long boil. On an AEG hob the residual heat indicator is a red light, which is why "AEG hob red light stays on" is one of the ways this question gets asked. If it goes out once the glass is cool to the touch, there is nothing to fix. If it stays lit on a stone-cold hob, the temperature sensor for that zone has failed high, and the zone will usually still cook; that is a nuisance repair rather than a hazard, and a job for an engineer because the sensor is bonded to the underside of the glass.

A ring that is actually still heating after you have turned it off is the other problem, and it is the one to take seriously. On a ceramic or solid-plate hob, and on the hob of most Belling, Rangemaster and Stoves range cookers, each ring is controlled by an energy regulator, a mechanical switch that cycles the element on and off to hold the setting. When the contacts inside it weld or the spring breaks, the ring stays on at full power regardless of the knob, and the only thing that stops it is the cooker switch on the wall. On an induction or touch-control ceramic hob the same failure lives in a relay or a triac on the power board, and the symptom is a zone that keeps going with its display showing nothing, or showing a power level you cannot change. Either way, the appliance has lost the ability to switch that zone off, and it must be isolated at the wall and not used until the part is replaced. This is not a fault you wait out.

Between those two sit a handful of things that look like a stuck ring and are not. A radiant ring on a low setting glows and dims as the regulator cycles, and a ring on its lowest simmer setting can glow for a surprisingly long time after switching off while the element cools. A pan left on an induction zone with the zone still selected, a knob that has been turned all the way round rather than off, a child lock that is stopping the off command from registering, or a spill across the touch panel that is holding a control down all produce a ring that seems to ignore you. A hob with a stopwatch or timer function can also appear to restart on its own when the timer reaches zero and the zone was set to start rather than stop. Work through those first, because they are free, and because when you ring an engineer about a stuck ring the first thing they will ask is whether the wall switch stopped it.