I have a 98 m6, LT's, ORY and I am having o2 problems. I just replaced the two fronts with the 13111 and now it seems that they are giving me lean codes on (sensor 1 bank 1) (Sensor 1 bank 2) (sensor 2 bank 1) (sensor 2 bank 2) are these new o2's bad or what? Guy at Autozone told me that I need some spark plug foulers to move the o2 sensor so that it would read correctly is this correct?

 

Thats done toyotas, you do that on the rear o2 when you remove the cat and the ecm never knows it's gone when you move the sensor away from the heat.
For you it would be hit or miss, it wouldn't be worth the effort, and I've never heard of it being done with an LS1.
Why did you change them?

 

They were bad. They fixed the problem with the car running in open loop and the poor gas milage but now that damn light stays on and that's what I'm getting.

 

It's hard to believe that 4 sensors are bad rather than believing that one or more are working right, and the car is really lean. Check your fuel pressure at the rail. If it's good, find someone with a scanner who knows what they are looking at to see what the MAF is reporting, or maybe see if you can borrow a friends MAF and see if the codes go away and stay.

 

I checked the fuel pressure at the rail and it was good, and changed the fuel filter. Still the codes remain.

 

check the maf like said above. i have the same 02's on my car on the front banks, my car runs good (little rich, but w/e) with no tune.