2001 Chrysler Intrepid 2.7L Engine - Fault Code P1684 Explained

I recently purchased a 2001 Chrysler Intrepid with a 2.7L engine that has accumulated 117,000 miles, and despite its age, it appears to be well-maintained. After performing a routine tune-up and replacing the spark plugs, I started receiving fault code P16804. I'm wondering if this code could have been triggered by the spark plug replacement or if there's another underlying cause. The vehicle has reliably started over 50 times since purchase, with no other noticeable issues beyond the recent maintenance. While I understand that P1684 is not a critical fault, I'm seeking clarification on what this code means and whether it might be related to my recent work on the engine. I also recently posted about another issue—P0442—and have already replaced the aftermarket gas cap. Any insights or advice on how to interpret P1684 in a 2001 Intrepid with a 2.7L engine would be greatly appreciated.