I am going to start replacing the exhaust on my XJ tomorrow. I have all of the parts here including a new sensor from Bosch (part # not in front of me at this time). I bought it with the idea that I may not be able to get the old one out of the up pipe. I was able to get the old one out and saved it but I am looking for advice on whether I should reinstall the old one or use the new Bosch. I have no idea if the sensor is OEM and usually try to stick with if it ain't broke don't fix it. Then I can save the Bosch sensor for another time.

 

If the Jeep is running well and no codes are present, I would re-install the old one and save it for another time.

 

I have not checked the codes, not seen a CEL and it passed emissions at the beginning of the year.

 

I replaced both sensors when my fuel mileage bottomed out. No codes or CEL.

 

I would just use the old one again. Especially if its an NTK brand. XJs aren't too fond of Bosch O2 sensors.