Cooktop display shows an error or flashing: decode it by symptom

Your cooktop display shows an error or flashing — a letter, an odd number, one zone blinking, or a short beeped code. This article decodes those errors by symptom, not by the manufacturer's manual: what letters mean versus numbers, which fault is the cookware, which is overheating or a sensor, and which is already an electronics failure. At the end you get what you can safely try yourself and where the bench begins.

We only work with electric cooktops — induction and glass-ceramic (radiant) panels. No gas cooktops here, and why they barely have error codes at all we explain separately below.

When your cooktop display shows an error or flashing: read the signal first

A cooktop has no screen to write a full sentence, so it talks in short signals. Before you hunt for the exact code, work out the type of signal — that already halves the list of causes.

• A letter, or a letter with a number (E, F, E0, F7, C, U…). This is a real error key from the cooktop's internal program. The letter usually marks a category: "E" — error, "F" — fault, "U" — often a user-side problem, "C" — communication or Child lock. The number says which one exactly.
• A single flashing digit or one zone blinking. If one segment or the power level on a single zone is flashing, the issue is that zone or its cookware. If every zone flashes at once, the issue is the whole board or the power supply.
• Beeps with no letters. Many cooktops show a fault only with sound and flashing, not a code. Count the beeps and watch what flashes along with them — it is the same signal in another form.
• "- -" or "H" after cooking. This is usually not a fault: "H" (Hot) means the zone is still hot; dashes mean standby. Before you panic, make sure it really is an error symbol and not a status symbol.

The first step is always the same: note the exact symbol and what you were doing when it appeared (put a pan down, switched on a second zone, cooked for 20 minutes). Those two facts often decode the code faster than the manual.

Overheating, pan-detection and sensor errors

Most of the codes we see on the bench fall into three big categories — very different in cause and in whether you can deal with them yourself.

Pan detection (typically "U", flashing, repeated beeps). Induction only. The cooktop is looking for a ferromagnetic base and cannot find one. In most cases the cookware is to blame, not the cooktop: aluminium, copper, a thin or warped base, a pan too small for the zone. The check takes a second — a magnet sticks to a steel or cast-iron base, not to aluminium.

Overheating (typically "E2", "E", after some minutes of running). The inside or the surface has got too hot and the protection shuts the zone off. On induction this almost always means heat on the IGBT module or the coil — most often from a clogged cooling fan or blocked air vents underneath. On ceramic it tends to be the surface thermal limiter.

Sensor error (typically "F", or "E" with a high number). The cooktop "sees" a false temperature because the NTC sensor (thermistor) on the coil or under the surface is damaged or has a loose lead. The board shuts off for safety even when nothing is overheating. You will not check this without the bench.

Touch-panel faults versus electronics faults

A large share of "errors" on a modern cooktop are not an internal failure at all — it is the touch panel behaving oddly. Worth separating, because touch-panel symptoms look dramatic but are often harmless.

A touch-panel fault looks like this: the cooktop switches zones on or off by itself, power levels jump, the panel ignores your touch or reacts to something you are not touching. Typical causes:

1. Water, grease or an object on the sensors. Capacitive sensors "see" a water drop or a tea towel as a finger. Wipe the surface dry — that fixes a surprising number of cases.
2. Child lock. An "L" or a key symbol lights up and the cooktop ignores you. That is not a fault — hold the relevant button for 3–5 seconds to release it.
3. Steam from a pan rising straight over the panel strip — the sensors get briefly confused but return to normal once the steam clears.

An electronics fault looks like this: a steady letter-number code that comes back after a full power cut, one zone completely dead, a beep and an immediate shut-off the moment you switch on. That points to the NTC sensor, IGBT module, a relay or the control board — a job for the service centre.

The simple deciding test: wipe the surface dry and disconnect from the mains for a few minutes. If the "error" then disappears, it was a touch-panel or short-lived problem. If the code comes back, it is a real electronics failure.

When the code clears after a power cut, and when it returns

Whether the code survives a full power cut is the single most useful thing you can learn before diagnostics — the line between "momentary glitch" and "a part has failed".

The right reset: trip the cooktop's breaker in the distribution board for 2–3 minutes, not just a tap on the off button. Many induction cooktops in Riga flats have their own line and breaker — that is the one to switch off. Then switch on and watch.

• The code cleared and does not return — it was a one-off: a voltage spike, steam, water on the panel, a brief overheat. Keep using the cooktop and watch whether it repeats.
• The code returns at once, with nothing on the cooktop (no pan, cooking nothing) — a failed part the board reads constantly: NTC sensor, a board channel, a relay. That is bench work.
• The code returns only under load (when you put a pan on or after a few minutes) — the overheating or pan-detection category: fan, air vents, cookware, the sensor on the coil.
• The code jumps around, different symbols — often a power-supply or ribbon-cable problem; an unstable contact feeds the board garbled data.

Note which of these four scenarios your cooktop falls into — that one observation often saves half the diagnostic time.

Bosch, Siemens, Electrolux, AEG and Beko: the common hob codes

We deliberately do not give a precise per-model code list — the same letter from one manufacturer means different things across series, and inventing one would only mislead you. But the categories of the common codes are stable across brands, and they help you understand what you are dealing with:

Bosch and Siemens share one platform, so their code logic is almost identical; so do AEG and Electrolux. The practical point: if you know how one cooktop in the household behaves, a related brand behaves much the same.

Whatever the brand, the order is the same: identify the type of signal (letter/number/flashing), then the category (cookware / overheating / sensor / voltage / communication), check the cheap end (pan, vents, outlet), and only then bring it in. Take the model number with you (a label on the underside or side) — with that we find the exact meaning of your series' code.

Do gas cooktops have codes?

A classic gas cooktop with rotary knobs has no error codes at all — there is no processor to display them. If a gas burner won't light, clicks but won't catch, or burns unevenly, that is a mechanical or gas problem (a clogged burner, a damp igniter, a thermocouple fault), not a code. That is for a gas service; we do not work with gas.

Modern hybrid hobs and ovens with electronic control can have a display and codes, but those relate to the electronic part and oven sensors, not the burner itself. If your cooktop is electric — induction or glass-ceramic — and shows a code, that is squarely our field.

If you are not sure which cooktop you have, the companion article on how the two types heat and fail differently helps: induction cooktop not heating. If the code appeared together with a crack in the glass, see cracked glass-ceramic hob: repair or replace; do not use a cooktop cracked right through, and disconnect it from the mains.

What you can safely try yourself, step by step

Before you carry the cooktop in, these steps are safe and clear a fair share of "errors":

1. Wipe the surface and the panel strip dry. Water and grease on the sensors are the most common cause of a false alarm.
2. Check the child lock. If an "L" or a key is lit, hold the relevant button for 3–5 seconds.
3. Induction — test the pan with a magnet. Doesn't stick = unsuitable. Also check the pan is not too small for the zone.
4. Clear the underside air vents of dust and grease; listen for the cooling fan turning while the cooktop runs.
5. Full reset: trip the cooktop's breaker for 2–3 minutes, then switch on.
6. Note the exact code and which scenario it returns in (empty / with a pan / after some minutes).

This is where safe self-help ends. Do not open the cooktop casing — under the surface there is mains voltage, a live induction coil and charged capacitors. The NTC sensor, IGBT module, relay and board we check with instruments on the bench.