An automotive scan tool is an electronic device the technician uses to decode serial data, communicate with modules, diagnose problems, and sometimes reprogram vehicle control modules.

Remember that a scan tool is only as good as the user’s understanding of the data. When used with the proper reference materials, a scan tool can significantly help a knowledgeable, experienced technician performing computer-related diagnostics. Often the device is more than a help; it's a necessity. But it cannot solve problems by itself. Understanding the data and accurately interpreting the information displayed is the key. The technician, not the tool, is the diagnostician.

Four Types of Scan Tools are available: 

  1. Code Readers – They are inexpensive and quick but do not provide all the Global MODEs.
  2. Bluetooth for Smartphones – moderately priced but does not provide all the Global MODEs.
  3. Aftermarket with complete Global OBD II and Enhanced (OEM Level). 
  4. OEM factory specific, but may not include any, or all, of Global OBD II MODEs.

A scan tool can be Wired or Wireless (Bluetooth), handheld or PC based. To achieve a higher level of diagnostics, an essential Code Reader or Bluetooth for IOS and Smartphones will not do the job.

Two options are available when using an aftermarket scan tool, technician and there are advantages to both:

Global (EOBD) OBD II: 

  1. Does not identify the system by Make, Model, or Year. 
  2. Talks in standard Protocols to all systems. • Pre-CAN PIDS can be limited. 
  3. CAN PIDS can be extensive and provide some PIDS the Enhanced Scan Tool does not provide. 
  4. Can provide many PIDS similar to Enhanced OBD II but may identify them using different terminology. 
  5. If available, provide minimal Bi-Directional Testing using the EVAP Vent Solenoid.

Enhanced (OEM) OBD II: 

  1. Does identify the system by VIN, Make, Model, and Year. 
  2. Talks using Protocol specifically used by that manufacturer. 
  3. Can provide many PIDS similar to Global but may identify them using different terminology. 
  4. Can provide PIDS not found in Global OBD II. PIDS may be divided into pages. 
  5. Provides Bi-Directional Testing of specific Outputs. 
  6. It may provide reprogramming options.

Many times, with pre-Can OBD II, technicians would choose the enhanced side of the scan tool. This was because it offered more PIDs.