Okay as some of you know I bought this car a month ago, and it seems like I bought it right when things need to be done to it. In a way it is frustrating, but this car is such a dream to drive I am just going to bear it until I get it right. Here is what is happening now.

Check Engine light just came on but car still runs smooth as silk. I was told I have a rattle in one of my cat converters. If the cat converter caused the check engine light to come on wouldn't the car run rough?

Intermitent front end vibration. On the highway at times I get a vibration. When it is vibrating I will also feel it when braking. It only does it on the highway, and does not do it all the time. I have had all tires balanced, and I was told both front axles were recently replaced.

I don't know if I mentioned the dynamic range control light, or the need to get the radio code, but I need help with those to.

Please Help

 

You still need to buy a vag com so you can pull fault codes and what not. www.ross-tech.com
As for the check engine light, if the engine is running smooth it can be anything from a loose gas cap to any emmisions related componet that doesn't affect the engine performance. A cat coverter can throw a fault code and you won't notice any power loss in the engine unless its really plugged up. Think of you trying to blow through a straw thats kinked. If you feel the engine performing ok then i would say the cat is fine, but you still need to pull the codes to know for sure. You can rent a scan tool from autozone to get the fault code real quick, then post it here so we can figure out what it is.
If you can feel a vibration in the front end AND you feel the vibration in the brake pedal it means you have warped rotors. Which is to be expected on a used A8 with more than 80k on the clock. Just another thing you will have to change out with the front brake pads when you get around to it.
The dealer can pull the radio code for you, but they do charge a fee to get it.
I don't remember you ever telling us about the dynamic range control unit acting up.

 

Thanks for the reply. It is funny you mention I forgot about the dynamic range control unit. When I bought the car that is the only thing I knew was wrong from the beginning. I know that this is common with a used car, and I am going with the flow since I don't owe anything on the car. This car is just so amazing to drive, and I get compliments almost everyday. I am also glad about the vibration advice you gave me. What was throwing me off was I thought a warped rotor would vibrate all of the time. Are there any specific ones you would recommend, and is that an easy DIY. I usually do most of my own work especially brakes.

 

OEM rotors, or Brembo replacement rotors. OEM pads or equivalent. Stay away from ceramics on these cars, they tend to increase pedal effort, increase heat applied to the rotors warping them faster, and they crack the pads a lot. I think you can deal with a little brake dust...
The front brakes are very easy to change out, you just need to either pull the 7mm allan bolts for the pads, or pull the two large bolts (21mm or 22mm) and pull the entire carrier off the rotor. I usually use a really big channel lock to push the piston back in, or you can rent a tool. The rear pads require a tool that screws the piston back in, just in case you were planning on replacing them as well.

 

Thanks. I will go with the Brembo rotors. I have heard nothing but good things about them. Now I have something to do this weekend.

 

I just had BOTH my converters replaced (under warranty). 5 shorted coils (as a result of a professional engine shampoo) caused fuel buildup in the converters - by way of engine misfire. Cats were $1200 each and the book called for nearly 20 hours of labour. The car was running fine however it was a bit "rich" as a result of the clogged converters. Thank goodness for a warranty. Also, cats are covered for an extended period as per government regulations - maybe call your local Audi dealer?

If your "check engine" light is flashing, pull over and call for a tow. So I'm told...

 

Just curious what year is your A8? The warranty on the cats is 80K, and my car is over that. I found an aftermarket cat for $180.00 that will cost me $100.00 to have installed. My cat is in the area of the front seats, and is very easy to get at.