FYI, I also got the Service Engine Soon (SES) light, and took it to Advance Auto to read and go the P1131 code. I did some research and am very thankful to all those who have posted about their issues and how they resolved them, as I was able to do some troubleshooting and finally fix the issue by purchasing a new Swirl Control Valve Solenoid... There were some things I learned along the way that I'd like to share:
1. Mine is a 2003 Pathfinder, and the SCV Solenoid diagram is somewhat different from the prior year models - the 2003 also had that black vaccuum box that others don't; the FSM specific to the 2003 model has the correct diagram. Mine is just like the pictures that Carlsbad posted above, in 2013
2. the FSM for the 2003 model has specific instructions for the P1131 code, whereas prior models don't even list the P1131 code and instead deal with the SCV Solenoid under the P1130 code - so make sure you're using the manual specific to your model year
3. because the 2003 model has that black vaccuum box, the part number for the replacement SCV Solenoid is specific - in my case, it's part number 14956-1P101, which I odered for just under $100 plus shipping from
https://www.nissanpartsdeal.com It's the solenoid with the green plastic, NOT the brown one.
4. I had tried blowing out the hoses and resetting the code, but it just kept coming back. You can re-set the code by using a code reader, or just by disconnecting your battery for 24 hours - that's what I did.
5. Actually replacing the green SCV Solenoid is a piece of cake: start by loosening all the hoses while it's still attached, and spring the nut on the back of the solenoid with a bit of WD40; then loosen both 10mm bolts holding the black vaccuum box so you can tilt it up and get to the nut on the back of the old solenoid; remove the nut, put in the new solenoid, connect hoses and bolt the vaccuum box back in
6. Don't forget to re-set the SES light
Thanks to all you who have posted before me!
Nico G