My 2002 Nissan Sentra’s check engine light keeps coming on. It came on about three weeks ago, and our mechanic replaced an oxygen sensor. Two or three days later, it came back on. He figured the first sensor was faulty, and replaced it with another. The light came on as I was driving away from the place. The mechanic replaced some of the wires. And now, a week after that, the light came on again.
Help! Any thought on what it might be or what I should do from here?