hey every1

i have a 95 infiniti G20 with about 50k miles on it and ive had it for just over a year.For passing the inspection i had to change the master cylinder after which it seemed ok. but recently my ABS light on the dashboard was coming on after i drive my car for a little while. i replaced the front ABS sensors and also the brake pads and the ABS relays. The light is still on. i took it to autozone and they scanned the car for me and told me the fault code is "P0325" which is the "knock sensor 1 circuit malfunction". now im in a dilemma... should i change the knock sensor or should i just take it to the dealer??
Also where the hell is this Knock sensor Located on the infiniti??? and how do i get to it??
i would appreciate any responses.... thanks folks.

ravi