Hi I just bought a used 2002 Sierra 2500hd crew cab 4x4. A few days after I bought it the check engine light came on. I bought a obdii scanner on ebay and found it shows P0332. I reset the computer but a few days later the check engine light came back and again showing code P0332. In the book it say knock sensor 2 {rear} Low voltage. What is most likely the problem? How to diagnose further?