So last month my exhaust pipe broke before the catalytic converter and i had to replace the front pipe on the left side of the engine (2.8l 30v) and i replaced the o2 sensors behind the cat and reused the one before the cat. Now my check engine light is on and i am passed due for inspection. So now i believe these sensors are what are causing my check engine light to come on. So my questions are how can i check if it is the o2 sensors that have failed and are causing this error code? will i need to scan the computer with a vag-com? and how hard will replacing the pre-cat o2 sensor while the pipe is still connected to the car be?

I have tried finding people in my area who have a vag-com with no success, so if anyone has one or knows someone in the clinton, nj area that would be great. also i purchased an ebay vag-com cable and was never able to get it to work. I could get the software to work but when i would scan the car it would say my car is not obdII compliant. If anyone knows a solution that would also be great.

Car is a 99 a4 2.8lqm

Any help would be great cause i would like to be legal on the road as soon as possible. Thank you

 

So ive done some additional research on the problem of why i couldn't get my vag-com to work, and i noticed a thread on the subject. About how if there is k-line problems the scan tool will not work. The tread talks about disconnected the cluster and radio and such which is a little labor intensive. But my car came with an aftermarket radio when i bought it and ive removed it when i tried to scan the car before and it didn't work. But what i did notice it the dumbass who put it in did a **** job of cutting up and taping the wiring harness to install the aftermarket radio. So now my question is how can i diagnose the wiring harness to make sure the k-line is functioning properly so tht i can scan the car.

 

Autozone scans for free

 

I wish i knew that autozone offered free scans but my problem is more than that. I picked up a multi-meter today to check the pins on the obd2 connector and my k-line was about 10V, which i believe is above normal. Since i have an aftermarket radio that is were i started my diagnosis. But the wiring harness was cut up and sliced so poorly im having trouble trying to reverse engineer what they did. I will post a pic later so you guys can have a good laugh over it, but for now can anyone post a pic (in color not the bentley repair guide i have that) so that i can see what it is supposed to look like stock.