A scan tool is a piece of equipment that can communicate with a vehicle's diagnostic system.

All vehicles manufactured in the USA since 1996 are required to be OBD-II compliant. OBD stands for On-Board Diagnostics, and the Roman numeral for two indicates that it is the second generation of the OBD system. The Society of Automotive Engineers (SAE) is responsible for defining on-board diagnostics as well as many other automotive standards.

All modern vehicles are controlled primarily by an on-board computer. The computer monitors various sensors and uses the collected data to control the state of the vehicle. If a potential problem is found by one of the sensor readings, the computer will store a Diagnostic Trouble Code (DTC) in memory. When a critical DTC is stored, the vehicle’s check engine light will illuminate. Then the problem can be easily discovered by using an OBD-II scan tool to read the stored DTC(s). Once the problem is identified it can be repaired, and then the OBD-II scan tool can be used to clear the DTC(s) from memory, thus resetting the check engine light.

When your vehicle first starts up the on-board diagnostic system performs a series of tests to verify that your oxygen sensors and other emission-related systems are working properly. Vehicle inspectors are required to check the results of these tests using a scan tool before passing your vehicle.

ProScan is a full-featured OBD-II scan tool with many extra functionalities as well!