Why does the check engine light remain on with no performance problems? on 2001 Hyundai Elantra

I had my exhaust system replaced and my O-2 sensor replaced in the exhaust pipe.

Asked by for the 2001 Hyundai Elantra
1 answer
There is most likely another problem with the car that is turning the check engine light on. We see more functioning 02 sensors repalced than any other part on a car.I would suggest you have someone diagnose the problem