Audi A4 B5 Avant 1998. I have a fault code 00578 Knock Sensor Regulation Cyl 2 08-10 Control Limit Surpassed - Intermittent I have replaced the injector to Cylinder 2 and am looking to replace the knock sensor. . . if only I could find it! Does anyone know where this is located on the diesel 2.5tdi?