I recently purchased a 2019 grand caravan gt 3.6l. Been getting an intermittent p219b code and now all of a sudden P0420 code.

 

I got those codes, and then eventually P0300 and P0303. I have a ticking rocker arm, and I suspect they are all related to the rocker arm. I ordered a rocker and lifter, and I will investigate when the parts arrive.