Car scanners plug into your car's system and output the fault codes associated with problems in your car. You can then look up these fault codes to determine out what's wrong with your system. These tools allow you to perform a variety of tasks -- even resetting your "check engine" light.
OBDLink 2.0
On-board diagnostics (OBD) is the process by which vehicles run tests on their systems, and scanners can read this information to determine how efficiently the vehicle is performing. The OBDLink 2.0 tool allows you to obtain freeze frame data about your vehicle, and you can reset your check engine light once the problem is fixed. Other features of this tool include the ability to read and remove fault codes, and you can determine the fuel efficiency of your vehicle. This tool comes with a universal serial bus (USB) interface, and you have the option to make this tool either Bluetooth or wireless Internet (Wi-Fi) enabled. The OBDLink 2.0 is compatible with all cars and light trucks made between 1996 and 2010. As of 2010, this tool costs between $99.95 and $149.95.
Actron 9410
The Actron 9410 code reader allows you to read and erase fault codes, and you can reset your check engine light with this device. It also will distinguish codes based on whether or not the error could damage your engine. To use this device, you plug it into your system, and hit the read button. This tool is for consumers, and it uses a simple interface to help you run scans on your system. This tool costs approximately $137 in 2010, and it is compatible with all vehicles made since 1996. This is a handheld tool, and the codes will print out on the device's screen.
AutoTap Express DIY
This tool allows you to figure out common vehicle problems, including why your system failed an emissions test and why your car isn't fuel efficient. AutoTap Express DIY is a combination handheld device and software program, and the software program is for either a netbook or a laptop, allowing you to check problems on the go. The device plugs into the port located under your dashboard, and you can use this tool on either a car or light truck. This tool is compatible with Windows 2000 with Service Pack 4, XP with Service Pack 3, Vista with Service Pack 1 and 7. AutoTap Express DIY costs between $99.95 and $199.95.