Check engine light FYI
Light came on at 30,500 mile on my 2012 Grand Cherokee 3.6L. I took it to the dealer and a code noting number 2 cylinder misfire was present. Dealer said that there was a bad set of 3.6L cylinder heads machined with the valve seat depth wrong and over time would not seat properly causing a misfire. This made sense as it did develop a rough idle.
Dealer replaced the entire head, light is out and it idles smooth.