I had this error in conjunction with the P1450 code (unable to bleed vacuum in gas tank) which was causing delayed starts after filling up with gas. In a previous experience with a different vehicle, I was throwing essentially the same code but on each side of the engine and it was caused by a vacuum leak.
I ended up replacing the vacuum purge value that sits right on the back of the intake manifold and this has so far taken care of the P1450, P2196 and P2198 codes. I no longer have the delayed starts after filling up with gas.