codes 328 & 1491

[telriv]

I have a 2002 Frontier, 3.3L V-6, 92K miles. Have a code 328, knock sensor voltage high. I know that this sensor is a PIA to replace & also a bad timing chain/worn guides can also trigger the knock sensor. I don't hear any tell tale rattling upon cold start indicating a loose chain/guides. Was mentioned that a new sensor can be installed in a different location. Any threads, pictures, explanations to go to/articles explaining this????
Also have a code 1491. Vacuum cutoff valve bypass valve. Where is this located?? How to test?? Threads or articles explaining the process, troubleshooting???
Thanks for any & all help & suggestions.

Tom T.

[Rev_D21]

NICO has factory service manuals in pdf format at www.nicoclub.com/FSM and we do have one for the 2002 Frontier. Hopefully that gets you in the right area. Feel free to download the entire manual to your computer for future reference. Welcome to NICO!

[telriv]

Unfortunately with my dial-up & computer it would probably take a week to unload that file. Thank you for providing that reference Reverend D21. Anyone with any other thoughts or suggestions???? I thought maybe I would get more replies than one as from my researching these are not uncommon problems.
Thank you all for the welcome.

Tom T.