Bosch [Temperature too high]what it means

Two menu labels in BSH’s microwave dataset — "Temperature too high" and ‘"000" flashes’ — return exactly the same answer, which is that the appliance has not cooled down completely and that you should wait until it has. Before taking that at face value for the zeros, read Bosch’s own manuals, because they disagree. The UK manual for the Serie 4 built-in BFL523 and BFL524 family has the troubleshooting row "Three zeros flash on the display. There has been a power cut. Reset the time.", and its set-up section says that after connecting the appliance to the power or following a power cut, a signal sounds and several zeros are shown until you set the clock.

Siemens’ iQ500 BF525LM manual prints the same rows, and the database itself, in its malfunction group rather than its error-code group, says "Power supply was interrupted. Reset the time." So on a current built-in, three flashing zeros are the clock asking to be set after an interruption, and setting it is the first thing to do; the cooling reading belongs to whichever older range the database entry was written for. Where the display genuinely says the temperature is too high, the brevity of BSH’s answer is a fair reflection of what is happening: this is not a fault, it is an appliance declining to start a job it cannot finish safely. What makes it worth explaining is that the behaviour is invisible from the outside. A microwave contains a cooling fan whose job is to move air across the magnetron and the electronics, and thermal protection watching both. If the cavity or the components around it are still hot from the last thing you cooked, starting again immediately means beginning with no thermal headroom, and the appliance would be into its cut-outs within minutes. So it refuses at the start rather than stopping half-way through.

The trigger is normal use. Two or three things reheated back to back, one long defrost, or a grill or combination programme on a model that has one will all leave an appliance hot enough to decline. The thing that turns this from a two-minute wait into a recurring complaint is where the appliance lives. Ventilation is decided by installation, not by the microwave. A countertop model pushed back against a wall with a bread bin on top of it, or a built-in fitted into a housing without the clearances its instructions specify, recirculates its own exhaust and never properly cools. That is an appliance that will keep saying this, and no part will fix it. So the immediate answer is to wait, and the real question is whether it has enough air.

1. 1

   If the display is three flashing zeros, set the clock first. Bosch’s UK manuals say the zeros mean there has been a power cut and the time needs resetting — on the Serie 4 built-in you press the clock field, set the time with the rotary selector and press the clock field again — and a display that then behaves normally was never hot.

2. 2

   If the message is about temperature, open the door and leave it open. BSH’s answer is to wait, and an open door lets the cavity dump heat far faster than a closed one. Give it fifteen to twenty minutes rather than two; if it clears in that time, nothing is wrong with the appliance.

3. 3

   While you wait, find the ventilation grilles — usually at the back and along the sides or top — and make sure nothing is against them. Take anything off the top of the appliance.

4. 4

   Pull a countertop model forward so there is a clear gap behind it. Manufacturers specify these clearances and installations routinely ignore them.

5. 5

   Listen for the fan next time it runs. It should be clearly audible. A fan you cannot hear, or one that sounds laboured, is worth mentioning when you book.

6. 6

   If the message is there on an appliance that has been off overnight, stop waiting and book a repair — the sensing is wrong rather than the temperature.