I have a 2000 GA SE with a 2.4 and 160k miles. I was looking in a repair manual and I did not know anything about a knock sensor. I am wondering if maybe it ain't bad because when the car is under load(A/C, heat, ect) the engine makes a noticeable knocking sound. Is this a normal sound for these Quad 4's or could the sensor be bad?

YOu would need to have it scanned to find out if the sensors bad.
Your knocking could be something else..... :eek:

if it wasn't working would it throw a check engine light?

Not always. If was working within the threshold of the sensro perameters it might not, if was totaly broken or has a bad circuit then it would throw a DTC.

Though, if its pounding/knocking like a hammer beating your engine block... its probly not the sensor.

Go get it scanned !