It is if you aren’t getting those codes from the computer which is why this problem is so prevalent and with no answers on any of the forums addressing it. You are applying logic for other vehicles and problems to this very specific issue. I believe you have fixed lots of things on lots of cars but this problem is specific to this vehicle in this year range. It is important that other advice does not get mistaken for the right answer for the issue the OP is describing or someone might just buy another 180° thermostat and never fix their problem. I know this because i searched every forum I could find and not one had a solution that worked because none of the answers explain that you must use a 195° thermostat. I’m not trying to disparage you or your answer but it’s important to be accurate and specific to actually help this issue get fixed for the OP. My point is this is not a stuck open thermostat and if OP pulled theirs out and tested it, they would assume it was fine and probably put it back in.