The engine light recently came on on my 02 1500 with the 5.9 v8. Did a little research on it and said it was the downstream o2 sensor. Well i replaced it and the light is still on. I'm also getting poor fuel mileage about 2 miles less per gallon. Any ideas on what the problem could be?

 

Maybe you need to disconnect the battery overnite and reset the system.

 

What brand o2 did you use?

 

bosch

 

Try a Denso or NTK. They are what works best and most guys have the best luck with in a 5.9