#1 02 sensor for O/R XPipe?

It sounds like you are in need of MIL Eliminators, they will turn off your check engine light. Apologies for the lengthy explanation, here is a quick overview:

Your check engine light (assuming it is ONLY on because of your off-road pipe right now), is NOT causing you to run rich or lose horsepower.

The lack of catalytic converters on your off-road pipe is what is responsible for the rear O2 sensors sending the signal to your car's computer that "something is wrong." The only thing that is "wrong" right now is the voltage at the rear O2 sensors - they are reading at an incorrect voltage signal due to the lack of catalytic converters. Installing a set of MIL Elims on the rear O2 sensors will "trick" the voltage into being read at the "proper" level and the check engine light should go away (provided your car does not have any other problems*).

*If your car's check engine light was on before this install, you should get the codes read so you know what other problems exist.

Now, as far as the car "running rich" - only your front O2 sensors are responsible for air/fuel input, not the rear O2 sensors. If one of your front O2 sensors were damaged or not responding properly, then your car would "run rich" - the computer would remove timing or add fuel so the engine runs "safely." This is just a brief "nutshell" explanation.

It is very common (usually a matter of "when," not "if") for the check engine light to illuminate after several drive cycles once someone has installed an off-road midpipe. Again, this happens because the rear O2 sensors are now reading a "different" voltage that is allowed by the car's computer, due to the lack of cats, which in turn trips the check engine light.

This can be avoided by using MIL Eliminators. You can also make a homemade version on your own (using parts from Radio Shack), or purchase the "plug-in" type MIL Eliminators (I believe Dallas Mustang sells these). I personally like the ones from Pony Express Performance ( www.ponyexpressperformance.com )because they cost less than the plug-in style ones and are simple to wire in.

Just my .02

Like the above poster stated very well, get MIL eliminators first, then have autozone erase your code for you. If you get a MIL after that, have autozone pull the code, and let us know what it is.

sgarlic said:

Like the above poster stated very well, get MIL eliminators first, then have autozone erase your code for you. If you get a MIL after that, have autozone pull the code, and let us know what it is.

Click to expand...

I 2nd that statement.