Long time reader...first time needing advice so thanks in advance. I have a 2004 Disco SE with almost 100k on it. Completed the 90k service. Had SE light come on, pulled codes and based on that I got a new gas cap and MAF sensor. The final code was O2 sensor-bank 1 sensor 1. I changed both front O2 sensors...reset the SE light and all was fine. I had no codes and engine was running great for 2-3 wks. RIGHT when I was about to get it inspected SE light came on and it's the O2 sensor-bank 1 sensor 1 again and the truck is running rough. Spoke to a mechanic and was told that it's unlikely the new O2 sensor is bad and that I may have oil leaking internally causing residue to accumulate on the sensor.

Has anyone had experience with this before? There's plenty in here regarding addressing old O2 sensors but unable to find anything resembling my problem

 

did you check connector plug to make sure it be clean and making solid contact?

 

spray the heck out of them with electrical cleaner while they are snapped together worked for me.

 

Connectors appear clean and connected.

Agthird are you saying to spray the sensor itself?