Why does my induction hob not recognise my pan?

An induction ring senses the pan by the electrical load it presents when the coil energises. Anything that weakens that coupling — the wrong metal, too little of it, or too much distance — reads to the hob as no pan at all. The refusal is nearly always the pan, and the checks are quick enough that you can rule the pan out before suspecting the appliance.

Step by step

1. Test the base with a magnet, and judge the grip.A fridge magnet must grip the centre of the base firmly. A weak pull, or grip only at the outer rim, means there is too little ferrous material for the hob to couple to. This single test settles the majority of cases.
2. Measure the base diameter against the ring's minimum.Every ring has a stated minimum pan diameter, typically around 12cm on a standard ring and larger on a boost or bridge zone. A small milk pan on a large ring is the classic refusal, and the fix is simply to move it to a smaller ring.
3. Check the base is flat by rocking it on the glass.A base warped into a dome touches only in a narrow ring, which weakens the coupling badly. Warping comes from heating a pan empty or plunging a hot pan into cold water, and it is not reversible.
4. Centre the pan on the ring.The coil senses what is over its middle. A pan pushed towards the edge of its ring can be refused even though it works perfectly when centred, and this is a surprisingly common cause on hobs with rings marked close together.
5. Remove anything between the pan and the glass.A silicone mat, a sheet of baking paper used to protect the glass, a scratch protector, foil, or a heat diffuser disc all increase the distance and can break detection. Induction hobs are designed for the pan to sit directly on the glass.
6. Swap the pan and the ring to isolate the fault.Try a pan you know works on the suspect ring, and try the suspect pan on a ring you know works. Pan fails everywhere: the pan. Every pan fails on one ring only: that ring's coil or its driver board, which is an engineer job.
7. Read the error code if there is one.Most hobs distinguish a missing pan — usually a flashing pan pictogram or a U — from a genuine fault code such as E followed by a number. A code beginning with E and a persistent one at that is worth quoting to an engineer rather than working around.

Tips

• Cast iron and enamelled steel always work. Fully clad stainless is usually fine. The problem pans are aluminium, copper, and light stainless with no ferrous disc.
• A pan that worked and now does not is very often a base that has warped. Put a straight edge across it and look at the light underneath.
• Induction interface discs exist for non-magnetic pans. They work, poorly — they reintroduce exactly the two-stage heat transfer that induction removes, and they run very hot on top of the glass.
• If the hob detects the pan and then loses it during cooking, check the pan is not being lifted by a spoon or tilted on a warped base rather than assuming an intermittent hob fault.

Common mistakes

• Assuming stainless steel always works — Stainless is only magnetic in some grades. Plenty of good stainless pans are entirely non-magnetic, and the only test that matters is a magnet on the base of that specific pan.
• Using a protective mat under the pan — It adds distance the field has to cross and is a common cause of a pan that used to be recognised suddenly not being. It also traps heat against the glass.

If it doesn't work