to my uncles shop. Put if on the Vag the codes came up P0432 for mainbank of O2 sensors. My ? is my car is an 99 A4 quattro it has 97,000 miles. So do you think i would be better of changing the sensors first or giving the car a tune up first then seeing if the codes go away. My reasoning is that the car might not be running good enough to give the O2 sensors a reading which is throwing the codes. What do you guys think?

 

No thats a code for the cat converters reporting that its crapped out on bank 2.
So what you need is a new cat converter on the driver's side.

 

Do u really think thats what it is? I had it at this shop buy my house and they specialize in exhaust they said it was fine. My uncle was saying the O2 sensors in the front were acting funny not getting a reading but the backs were working fine.

 

How long has your uncle been working on cars? Yes im sure, if there was a problem with the O2 sensors it would throw a fault for the O2 sensor, plus the front O2 sensor has nothing to do with the cat converter, only the rear one.
Our ECM's are very sensitive to failing cat converters, there is a TSB (technical service bulletin) for re-flashing the ECM to make it less sensitive, so you might wanna ask the dealer if your car has been flashed yet. You have to provide them with the VIN number.

 

Cool man thanks for the advice. i guess i'll just have take it someplace. How much do u think this could cost?

 

The re-flash or cat replacement would have been covered under 80,000 federal emmisions warranty, but since yours is 97k your out of luck.
For the re-flash its about 1 hour of labor, lets say $80.
For the cat replacement your looking around $1,000 for a factory cat converter installed.

 

well isn't that some ****!! why couldn't this happen about yr ago. I just want the thing to get fixed and run better. Would u recommend a tune up? What would u consider a normal idle? Cause lately i've been having a little trouble with the idle

 

Idle problems usually stem from the MAF and throttle body. Take out the MAF sensor and use some electrical contact cleaner to clean off the element. Change the air filter and use some brake cleaner/electrical contact cleaner to clean off the throttle body valve. That or shoot some carb cleaner into the intake while someone is flooring the engine to break off all the carbon in the intake.
A "normal" idle i guess would be around 800-1,000 RPM and doesn't vary from that very much.

 

Should i buy both sides for the cats or should i just buy one side at a time?

 

If one fails then the other usually isn't far behind, so you can do either, maybe the other one won't fail, who knows.
You should first check to see if the ECM re-flash has been performed, you might not need any cats.