just installed new headers on my 3.8 and three days later service engine light came on.
had it scanned and found 02 sensor after the cat. was not working. wondering what impack
the headers have on the sensor and if replacing it would solve my problem.

 

What kind of headers did you get? I would say it's more of a coincidence than anything.

 

pasesetters headers

 

Maybe the sensorwas unplugged, and perhaps got forgotten about when it came time to hook everything back up...

 

yes i agree, check to see if it is properly connected