I have a 2000 A6 2.7T that won't start. I purchased a Ross-Tech VAG-COM to see what codes it was throwing but I only get the same 2 codes that were showing when I bought the car (& it ran fine then). The codes are 16486-MAF, 17521-O2 sensor. Physically it sounded like a fuel issue because the car would crank over then the motor would shut off. A few hours later the car started fine. The next day it wouldn't start. Then 2 days later it started fine, then hasn't started since.
I'm confused because I'm not getting any other any other codes like fuelpump or relay, but I didn't think a MAF or O2 problem would cause the car to not start, especially intermittently.
I just don't really want to spend the money on the expensive *** O2 sensor if it's not gonna fix the problem. At least the fuel pump relay is only about $40 at the dealership.

Any suggestions would be greatly appreciated.

 

id definately start with a maf.. that could cause a no start scenario .. try unplugging the maf and see if it starts.. your gonna have to have both parts sometime anyway...

 

I did try unplugging the MAF a few days ago but it still didn't start.