The German carmaker Volkswagen (VW) first released the Jetta, a passenger car, in 1979 and continues to manufacture it in 2010. A diagnostic scan tool plugs into your onboard diagnostic (OBD) system and reads the diagnostic trouble codes (DTCs) associated with the vehicle problem you are experiencing. One of the two main types of OBD systems, the OBD-I system, came with vehicles made prior to 1996. This system was car manufacturer specific, meaning that each car had its own DTCs. OBD-II systems, found in vehicles made after 1996, use generic DTCs relevant to all types of vehicles.

VAG-COM

The VAG-COM Diagnostic System --- made for Audi, Volkswagen, Skoda and SEAT vehicles made from 1990 to 2010 --- plugs into your OBD system and uses a universal serial bus (USB) cable to plug into your computer. On your computer, you can download and save vehicle DTCs, or view graphs and logs of vehicle data. Compatible with controller area network (CAN) vehicles, the tool logs vehicle data as your car is running. The VAG-COM Diagnostic System has a database of more than 9,200 DTCs. The kit comes with a carrying case, cables, software CD and adapter, and it is compatible with Windows 98, 2000, XP and Vista. As of 2010, the system costs $599, and the hardware comes with a one-year warranty.

Baum

The Baum European Hand Scan Tool, a handheld scan tool with a large display for viewing vehicle data, is compatible with German, European and Asian vehicles, including Volkswagen, Audi, Subaru and Toyota. It works with OBD and CAN systems. Baum offers free hardware setup, as well as technical support in different languages. Contact the company for a price quote on this tool.

AutoHex

The AutoHex tool is compatible with the following vehicles: Honda, Kia, Citroen, Hyundai, Mercedes Benz, Volkswagen, Audi, BMW, Nissan, Peugeot and Toyota. It allows you to run diagnostics on different systems, including your antilock brake system (ABS), engine, air bags and transmission. This tool uses a graphical user interface (GUI), which helps you run commands without having to write codes or programming. It also comes with its own Windows Embedded Compact (CE) operating systems. Its 10.4-inch LCD screen features video graphics array (VGA) color and touch-screen capability. Contact the company for a price quote.