The engine light stays on, it has an 02 sensor. It may need a new cadillac converter and cv joint.

Check engine light on when tested it says bad o2 sensor did you replace 02 sensor it takes driveing it so many miles before light will go off give it couple days you dont need cadillac converter check engine light will go off cv joint they click as you turn dont let a mechanic sell you something you dont need its very rare for cadillac converters to go bad its common for o2 sensors to go bad like yours did but when 02 sensors are replaced it takes driveing it for awhile before it resets itself you also have more then one 02 sensor was then wrong one replaced they screw into your exaust manifold