When I bought my S4 used a little over two years ago, it came with 36,000 miles and an unknown history. The dealer had purchased it at auction and performed the CPO inspection, but it's history was otherwise unknown. Since I bought it, the car has been in 9 times, most of the time for service or some annoyance.

I've found myself wondering what sort of warranty work had been performed on the car prior to my ownership. I knew the car had come from Florida, but I had no details on the car's service history.

So, on a recent trip to the dealership, I bugged my Service Advisor for my car's Warranty/Service History. At first my SA balked, saying it was all code (if a car has been serviced at multiple dealerships, only AoA's systems will have the complete records). I don't have a picture of the print out, but it's a coded list with dates, order numbers, dealer IDs, and an identifying work code. These codes look like this:

"W2-6048"

It's the only clue as to what was done to the car, but you do have the ability to decode most of these. The prefix ("W2") appears to be an identifier for the type of warranty covering the work done. "W2" appears to be the standard warranty, "AM" is scheduled maintenance, and "UC" may be the CPO warranty.

The four-digit suffix ("6048") refers to a particular part replaced on the vehicle. With the help of this CPO Coverage List and some reasonable guessing, here's what I figured out:



Obviously the CPO list isn't complete since some items covered under Audi Assured aren't covered under Audi's CPO warranty, but I was able to reconcile the part descriptions against my own invoices.

Apparently the previous owner had some problems with the car. I was surprised to see the turbos had been replaced, some part of the clutch and/or transmission had work done, and the front brakes were replaced 3(!) times.

I'm not sure if I should be relieved or worried by my car's service history, but I am glad that I researched it.

For 2nd owners interested in recreating what I did, download the Excel file linked below and ask your Service Advisor for your car's service history. Even if the history is coded, you should be able to decipher it.

• My Warranty History with CPO Coverage List (Excel)

2008 Track days: Mid-Ohio, VIR, Barber