When a modern car's "check engine" light comes on, it means the car's computer has a message for a mechanic. These messages are delivered in the form of OBD II trouble codes, and can be read by anyone with the right machine and a little know-how. If you want to be able to diagnose your car's problems for yourself, it's a relatively simple process to set up everything you'll need to receive and decipher its trouble codes.

Determine If Your Vehicle Is OBD II Compliant

Unfortunately, not all vehicles are sophisticated enough electronically to have an onboard computer like modern cars do. Most cars made before 1996 likely won't be OBD II compliant, which means you won't be able to take diagnostics or check trouble codes using an OBD II reader of any kind.

If you aren't sure when your car was made or you want to double check whether its systems are OBD II compatible, there are two easy ways to do this. The first is to pop open the hood of your car and look for a sticker identifying its onboard systems. Cars that work with OBD II technology will have a sticker saying so next to the other stickers placed by the manufacturer.

Another option is to look inside the car for a connector that would allow you to interface with its computer. These connectors must be accessible without special tools, and are also required to be close to the driver. Common places for them include the steering column, near the ash tray or cigarette lighter, near the driver's feet, and around the air conditioner controls. If you know for certain your car is compatible but can't find the OBD II port, consult your manual or search online for answers.

Choose Your Method Of Reading Vehicle Data

Once you've located your car's port, it's time to decide what tools you'll use to read your car's messages. Standalone OBD II reader machines are common, but you can also use a wireless Bluetooth plug and a phone app if you choose.

Standalone machines tend to be inexpensive, with some costing less than $30. However, they also tend to be very simple and will usually just allow you the no-frills ability to read out trouble codes from your car's computer. They have to be plugged in to your car every time you use them, but since this is their only purpose, you won't have a problem leaving them in the vehicle until they're needed.

Bluetooth transmitters and their accompanying phone apps, on the other hand, can provide much more comprehensive information about your car''s well-being and also have other functions, such as tracking your driving habits and reminding you about maintenance. They tend to be more expensive due to this added functionality, and they do require you to have a smartphone or other Bluetooth-enabled device in order to use them.

Learn How To Decipher Trouble Codes

Depending on the device you use, your smartphone app may help you understand what the OBD II codes your car sends you actually mean. Still, if you choose to use a standalone code reader or you just want to fully understand what your car is saying, it's a good idea to know how to find the meaning of any trouble code.

Trouble codes are 5 characters long and consist of a leading letter followed by 4 numbers. From left to right, the characters of the code give you information about the issue with increasing specificity. Using an OBD II manual, you can look up the meaning of just about any code, which will enable you to locate and possibly diagnose the problem before your mechanic even gets their tools out.

A little knowledge goes a long way when it comes to understanding what your car is saying to you. Getting the equipment and knowledge necessary to understand trouble codes should cost you less than $100, but being able to monitor your car's well-being and understand problems when they arise will be worth every penny. Once you've diagnosed the problem with your car, you can take it into a volkswagen service to have the necessary repairs done.