Hello, on the Spectra the Knock sensor is located behind the intake manifold support bracket bolted directly to the engine block, these sensors are actually very easy to test if you are getting a trouble code for it. The test is to unbolt the sensor from the engine block ( I have actually tested these still bolted to the engine, but our procedure here reads to unbolt it). Unbolting it will also show you if there is rust build up under the sensor preventing a proper reading, but you unbolt the sensor, unplug it from the wiring harness and if you know how to use a digital volt meter, place you meter leads on terminals one and two and tap on the sensor. And you should get a reading of less than 1 volt. This sensor does not need to be plugged in for this test because it produces voltage on its own. If you do not get any reading the sensor is bad, if you do get a reading, its best on these to replace the sensor (they are usually pretty cheap) but also you are going to want to check the wiring harness for any damaged wires for that circuit. This will prevent the PCM from receiving a signal from the sensor and thus setting a trouble code also. The third wire is a sensor ground, some models have it and some don't, but your major concern is pin 1 and 2. Hope this helps.
Tuesday, September 20th, 2016 AT 2:45 AM