why does the check eng. light stays on all of the time on 2000 Cadillac DeVille

does it have anything to do with losing coolage

1 answer
You need to have your check engine light codes read to see what systems have a fault. If you are also loosing coolant, you could be at serious risk of damaging your engine. Once the technician knows what system has a fault, they can determine the exact cause and recommend a repair.