When I bought my car from the dealer used, the knock sensor light came on, and dealer told me that they reset it, and that if it comes on again, they would pay for a new sensor. What if it's not the sensor, but an actual knock in the engine? Would I hear it? Is there major problems associated with this engine message? Thank you, Chris Kennedy
Knock Sensor? on 2003 Chevrolet Avalanche 1500
by Verno in Janesville, WI on September 24, 2009
ANSWER by certified.ase.tech , September 24, 2009
The knock sensor doesn't usually set codes from engine knock. If it detects engine knock then the pcm retards timing, cuts back fuel, etc.. but does not actually set a code. If the sensor has voltage going to it from the pcm then just replace it but make sure if the place you bought your car from does it they don't just ground the wire. This will effectively turn off the light & eliminate the knock sensor.
ANSWER by lazy mechanic , January 16, 2012
My knock sensor went out on my 2003 avalanche. It's not an easy job the knock sensor is located inder the intake manifold. Normally this is the problem.