Abstract
Knock sensors usually are used to detect engine vibrations due to self-ignition processes at a spark ignition engine. In this paper a knock sensor is used to draw conclusions about the combustion or malfunctions at a common rail diesel engine. The sensor measures structural vibrations at the cylinder head. With the following methods we present an approach to analyse this signal. The aim is to observe existing functions or components of the system with respect to OBD (On Board Diagnosis).