2015 Dart SXT 2.4L Thermostat
 

According to local parts store, fault code indicates bad thermostat. It is slow to warm up so I would tend to agree. Question I have is has anybody here replaced theirs. It appears that housing, sender, etc. are sold as one piece. Also, not having a whole lot of luck locating it at any stores. Even RockAuto has none.
Are these engines difficult to refill with coolant without creating air pockets/blockages? I have quite a bit of experience with Caterpillar, Detroit Diesel, Cummins, etc., so I have some applicable skills.
Any advice much appreciated.