Hi
I replaced front cat (near radiator) and middle and rear mufflers because of cat code and holes in exhaust.
No more cat code or loud exhaust,
but now I keep getting P1491 Vacuum Cut Valve Bypass Valve Circuit.
I never got P1491 before so is it a coinsidence, related to my exhaust repair or a uncommon failure that just happened?
any ideas how to trouble shoot P1491 Vacuum Cut Valve Bypass Valve Circuit?

thanks

 

The P1491 code related to the vacuum system that sucks the fumes out of the gas tank, so I don't think that it is related to the exhaust system work. The Vacuum Cut Valve Bypass Valve and the Vacuum Cut Valve are located by the EVAP canister that is behind the driver's rear wheel.

The FSM has some diagnostic proceedures in it, so you should start there. It is in section EC. in the 2000 manual it is page EC-678, in the 2003 manual it is page EC-598. Other year's manuals are probably different from these. The first several pages of the EC section is an index and it is alphabetical, so look for P1491 on page 6 or so.

If you need to download a manual, go here:

http://www.nicoclub.com/FSM/maxima/

The file named fwd.pdf is the chapter index file for the rest.
The file named idx.pdf is the alphabetical index file for whole manual.