I have 98 with the 2.8. The check engine light was for a post cat bank 2. I replaced both cat's and all 4 O2 sensors. The light is still on. I have driven about 50 miles. Do I need to go to the dealer to have it cleared?

 

Did you unplug the battery since the work was done? If not I'd start with that and see if the CEL comes back.

 

RedA4 I sure hope you didn't do all of that because of one CEL code for a post CAT O2 sensor! If you've done nothing to clear the code, its going to be there. Most auto parts stores will let you use their OBD reader. Learn how to use it. Hook it up and clear the code. Then see what you've got.

 

That sounds awfully expensive

Where are you located? Plenty of members here have Vag-Com, scanners, etc. If you're local to any of them I'm sure they'd be happy to help

 

I have had the code cleared 3 times and it comes back in about 70 miles. So I changed out both along with O2. Both cat's were after market that I changed. I got the new ones from rockauto.com. They were OEM direct fit and they did fit perfect. I'm located in Schenectady, NY

 

So is the code the same every time? B2 S2? You have to start questioning the wiring back to the ECU....or even the ECU itself. There are several codes that involve the O2 sensors. Which code was it?

 

The code is P0432 Cat system efficiency below threshold (bank 2)

 

Ok, that's not post-cat: that's pre-cat.

check this...since you've replaced O2 sensor and cats, take a look for exhaust leaks. But never rule out a bad new O2 sensor. You really need a VAG-COM and a Bentley for some good information.

16816/P0432 - Ross-Tech Wiki

 

Where do you get a vag com and do you have to make sure it is for Audi?

 

VAG-COM is always for Audi. It reads the VW/Audi electronics modules. VAG-COM is what we all call it but it's kind of an old name...it's now VCDS. It's made by Ross Tech, read more here.

Ross-Tech: Home

You can get into it on the cheap (like I did and have regretted it) by buying an interface here, then registering VCDS lite at Ross Tech for another $99.

OBDTool.com

But I wish I had popped for the Ross Tech program where once you have their interface, any install of VCDS is activated. Then I could move between my garage PC and a laptop.

Do it Red. It will save you lots and lots of $$$$$.