Got hit with P1491 and P0302 out of the blue.
Car was idling rough, I figured it might be the ignition coil. When I checked, it was P0302 as well as P1491.

P1491 is EVAP vacuum cut valve/bypass circuit malfunction
Browsing the forum, this is not just one part.
Is it safe to drive the car?
Where do I start?
Does weather having anything to do with it. It was raining hard when it happened.

2000 infiniti i30

 

It is OK to drive the car.
The P0302 is a misfire on cylinder 2. Probably the ignition coil. Swap cylinder 2 ignition coils with cylinder 4 (or 6, doesn't matter) ad see if the code changes to P0304 (or P0306). If it does, you have a bad ignition coil.

The P1491 code is a valve back by the EVAP canister behind the left rear wheel. Click here - http://boredmder.com/FSMs/Infiniti/I30/2000/EC.pdf - and go to page 631 of the service manual for a parts drawing and page 632 for the diagnostics.

 

And if the code doesn't move to cylinder 4 or 6, then likely you are looking at a bad fuel injector. Check the easy stuff first though, like the spark plug.

 

Thanks DennisMik &,Wizard
Surprisingly, when I drove around the next day, both codes disappeared.
I swapped out the ignition coil anyway. It was an after market from the previous owner. Replaced with Hitachi.

It's been a few days. P1491 has not come back. It fixed itself!