Hello and thank you for your post. I am a master certified GM tech. If I can help you solve this today then I will, lets begin
ok there are 2 knock sensors on this vehicle
the drivers side is bank 1, the pass side is bank 2
bank 1 sensor is located as shown in this picture...
it's item #4
bank 2 sensor is as shown here...
its item #2
incidentally there is a bulletin that may apply to these sensors that I will copy to you here...
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
The customer concern may be a lack of power and a ses light on.
During diagnosis a technician may or may not find DTC P0326 P0328 or P0333.
When accelerating and low power is noticed, the knock retard may be seen as high as 15 degrees.
Complete the current SI diagnostics for any trouble code or symptom found. If DTCs P0326 P0328 P0333 are found, and low power has been verified, inspect for a wire harness chafing concern.
The wiring harness located on the left side of the engine may contact the front differential mounting bracket. Repair and reposition the wiring harness as needed. Evaluate the repairs and verify the knock retard readings are not excessive.
not sure if this is helpful but hopefully it will get you going in the right direction
let me know if you need additional help
OK. Can you give me the vin #?
ok. I just ran the vin to verify the options and that diagram should be correct.
let me check the next and previous model years and see if the location changed
ok, in 2006 the knock sensors are located under the intake manifold...
here is the pictures,
you must remove the intake to get at them but maybe you can peek under and see the wires to verify the positioning