Since I didnt have the more agressive equipment to clean the fuel injectors at the fuel rail, I used Sea Foam on the vaccum lines and gas tank instead. It took 3 tanks of Shell premium 93 oct and 3 cans of Sea Foam to finally get rid of the dreaded OBD 0131 code which means bank 1 too lean. Even then I replaced the 0-2 sensor but the codes kept coming back. $30 in sea foam fixed it without buying a single part or removing any. The whole problem was just carboned up injectors and other dirty parts. No more cheap junk gas for me. 600 miles and no eng light or codes. Watch the Youtube videos on this. Their pretty funny.
EDIT: Half can for 11 gal gas tank & the other half can goes into the vaccume line. It took me 3 tankfulls of gas total so everyone is gonna be different. You can tell when its done its job because when you add it to the vaccume line and rev the motor up and the smoke never appears then you know its as clean as its gonna get. The best way to clean fuel injectors is to take them out and give them an "Ultrasonic Bath" but whos got that kind of equipment. I dont know exactly where the problem was because the OBD code of 0131 will send you in 5 different areas. For all I know it couldve been dirty injectors or a dirty fuel pump, EGR valve or a combination of all. Its gone and thats all that counts. The Sea Foam will mess with the transmission
"Hold Light" which is why I reccomend just doing it in the driveway first and then after 10 minutes take the car out for a spin. Its gonna smoke on the interstate after you kick it down to 70 mph and then fades away. Next treatment comes on the next tank of premium gas. I always knew to put premium in my tank when we went up into the mountains on vacation because the air is thinner there but after that I used the crappy 87 oct gas. Never again. Re-set your codes again because the car will run a little crappy if you dont.