Drehzahlsensor des Getriebes ausgefallen

A sensor reporting the rotational speed of an input, intermediate or output shaft inside the gearbox.

These sensors are the transmission's only way of knowing what gear it is actually in. Dividing input speed by output speed gives the ratio being delivered; comparing that against the ratio commanded tells the module whether the gear engaged and whether anything is slipping. Most performance and slip codes in the transmission range are derived from that arithmetic, so losing one signal disables far more than one measurement.

The commonest cause is not the sensor. It reads a toothed wheel through the fluid, and metal particles clinging to a magnetic tip will silence it while the sensor itself tests perfectly. Debris is something every transmission produces as it wears, and it collects on exactly the part that must stay clear.

After that, the internal harness. It runs in hot fluid and passes through a connector in the case wall, which is a known point for wicking and corrosion.

Expect limp mode. Without a believable ratio the module stops making shift decisions and locks a gear — which is protection, not further damage.