I had the same thing a couple of years ago. Warranty fixed it, dealer mechanic had me in and out in under four hours; I had to travel 3 hours to get to a dealer warranty facility that is OK to do the work. Yes, in the Promaster, the top of the engine (so to speak) has to come off, more specifically, but not completely, an oil cooler that's in the V of the engine on top of it. If you had this engine in a pickup, it'd be a 20 minute job.....but you don't. So, I saw my van with the grill off, and a lot of front end stuff laid down on the ground just to get the mechanic access to the damned sensor. They told me it was a known problem, apparently Ram got a bunch of bad sensors. In any case, no troubles since, my only beef was the mechanic forgot to put my sheet of insect screen back that I had put behind the grill to catch bugs. Now, I need to pursue my first idea for that, which is what I had for many other vehicles. DeflectaShield made a winter/summer screen front combo, which used snaps screwed into the plastic grill. Had a quilted winter front with flaps to open for venting or not, and a screen front for summer, both utilizing the same snaps. Was a great product! Have to have an upholstery place make me a special one now. Have pattern done, just need to locate the proper snaps and get it made.