Actually at the time I replaced the O2 sensor I also cleaned the MAF and replaced the PCV valve. It was Bank 2 which was driver's side first sensor before converter because it was saying Bank 2 sensor 1. I only have a basic code retrieval scan tool. I'm trying to figure it out myself. There is no change in performance from idle to full throttle either. It's as smooth as the day it was new. I know it's one of those LEV models so I'm sure the Check Engine Light will go on for the slightest change in sensor readings.