Genuine BMW Knock/Ping Sensor - S54 (E46 M3, MZ3 S54, E85 Z4M)

This part is listed by BMW as BMW part number 12147839167 and is described as a Genuine BMW / OE knock sensor for S54 engines used in E46 M3, MZ3 S54, E85 Z4M models.

The knock sensor (or ping sensor) is an acoustic sensor mounted to the side of the engine block. It listens for a distinctive "ping" sound when engine detonation/misfires occur. If enough misfires are detected the ECU immediately makes adjustments for one or more cylinders to avoid engine damage. A failing knock sensor will trip the check engine light and fault code.

This is a Genuine BMW ping sensor with a two year warranty. Buying a Genuine part will usually be more expensive than an OEM or aftermarket brand but you are assured that it meets BMW's designs for fitment, performance, and longevity. It will also be the very latest design, incorporating any updates or revisions that an aftermarket brand typically will ignore.