before you rip me, yes i know its a dodge forum, but the guys over on the nissan forum are usless. I have an 02 xterra throwin engine codes P1491 Manufacturer Control Auxiliary emission Controls and P0328 Knock Sensor 1 Circuit High Input Back 1 or 1 Sensor. ive never heard of a knock sensor before. whats it do? and the P1491 code...what the hell is that? any help with this would be greatly appreciated.

Thanks,
Steve

 

A knock sensor has to do with detonation. They run 95.99 at oreillys. As for the P1491 code, it is:

P1491
Secondary Switch Solenoid Circuit Malfunction

Whatever that means.

 

Even though it is like 100 bucks I would replace the knock sensor and clear the codes, see where that gets you. There is a chance that the codes came up together and since the knock sensor is the only concrete part involved, I would start there.

 

I imagine P1491 has to do with your EGR, the valve could be either stuck open or close. Could also be a code for a bad cat if it says "emission controls"

I can check into this more when I get home in a few hours.