Chrysler Repair: check engine light after replacing thermostat housing (or water compressor housing, Ive been told a couple names for it), sebring lxi, couple names

Question
I have a 2002 sebring LXi. It's a 2.7..I have had no problems with it until now. It overheated the other day and I found out I had a crack in the housing. Now the check engine light is on. In order to fix that I had a diagnostic done at autozone, got the part and changed that..now the light is off until you turn the car off and tighten the bolt to the battery, then it pops back on. Any ideas? Oh, and is it true that this car has one of the worst engines? my car has 50k miles and I've heard to sell it before 70k, is that true in your opinion?

Answer
ok few steps first ,what is the check engine light on  what code is it? Second the old part did it have a sensor in it and is there a new one in that one? If u change your oil every 3k and use 5w 30 U should not have any issue. I have a 98 Concorde with a 2.7 and have 157k on her. No probs  I just smoke a little when i start up from worn valve stem guides no biggie. IF u take care of teh car like the factory says to u should not have an issue.