Car code scanners let a mechanic or car owner understand and "read" the signals stored in a car's onboard computer. Using a computer language referred to as onboard diagnostic code, the scanner pulls the information from the car's computer memory and translates it to code numbers for the user. This information then helps diagnose what may be causing car operation problems, depending on which signal is being given by the car's sensors.
Purchase an OBD-II compliant code scanner for vehicle diagnostics either at your local automotive part store or online using your computer and Internet connection. Purchase a scanner that displays both the car code and category for best results. Some scanners provide only the code.
Open your car driver's side door and sit in the driver's seat. Find the code junction panel underneath the steering wheel or on the side of the console and open it. Do not confuse it with the fuse panel. Open the panel. Insert the connection end of the scanner into the junction panel for code reading.
Insert your car key into the ignition and turn the car to the "ON" position but don't start the car engine. Watch the scanner power up and read the car's computer. Allow the scanner time to process the codes saved on the car memory until they display on the scanner screen.
Use a notepad and pen to jot down the codes displayed on the scanner in case the car turns off. Turn the car off and disconnect the scanner when finished.
Refer to your code reference book or a website such as OBD-Codes to determine what issue the codes show. Use the code number to confirm the type of signal and warning message. Use a website or your code reference book to get a detailed description of the potential problem and which sensor is giving the signal.
