Ok, my car started REALLY running bad recently. I knew I was throwing a 0304 and an 0303 which I really wasn't worried about. The car was running ok for the most part. I recently started throwing an 0503 (rear upstream O2). I ended up buying all three O2 sensors for my car. I Installed the two upstream. I reset the ECU and ran the car. It was running great. The stumbling was gone when the car was cold. After a day, the ECU came back on (no shock since I didn't replace the rear O2). I recheck the codes (I HAD cleared the codes) and I am still getting 0304 (no shock) 0303 (again no shock) but now I am still getting 0503. The car is running better thank it has in weeks and I don't understand why 0503 has come back after the reset.

Also, does anyone have any advice on getting the O2 out of the cat? That thing looks welded to it. Did you use a wrench or socket? I noticed the rear is a much smaller socket than the fronts.

Yeah...I'm getting the KS soon too....

Anyone have any ideas about the 0503? I got all three sensors from courtesy nissan.

 

Or you could go the high flow route like I did.....


http://www.customenterprise.com/view.../vts/design004

 

How is getting a POINTLESS high flow cat helping solve his problem? Spray the O2 with some PB blaster and let it soak for a day or two. It will come off, trust me.

 

you use a wrench or a o2 sensor socket?

 

Just a regular wrench. I have the socket but abviously it's too big for the rear O2.