Join Date: Aug 2007
Location: Fort Collins, CO
Car Year: 1998
Car Model: Forester L 5MT
Feedback Score: 9 reviews
First, do not override the knock sensor - you might regret it some day.
Second, the only thing ECU checks is the impedance (resistance) of the sensor, so if that checks out (with a simple multimeter; should be ~500-600KOm, iirc), then it's the wiring. Get a wiring diagram and start testing/fixing.
P.S. Lack of knock sensor code does not necessarily means that the sensor is working well, as per (2) above. Also, rather easy to crack the sensor if overtightened.
P.P.S. Many knock sensor issues (timing retardation, hesitation) are caused by bad engine bay and other sensors' grounding. This will not bring up the
"knock sensor fault" code though.