Q: Are Code Readers and Scan Tools Different?

There are differences and similarities between code readers and scan tools. With the advent of the vehicle on board diagnostic system (OBD) there have been many different makers of scan tools and code readers. The code readers were the first to be made once the manufacturers allowed the information to be retrieved for a mechanic to access it.

Before there were code readers and scanners (scan tools), the mechanic would have to put the system into test mode and count a blinking light or a meter needle sweep to obtain a code, then hook up a tool called a breakout box. This box was installed between the vehicle computer and its wire harness. The mechanic would have to test each computer input and output using a multimeter to get the readings of sensors. This was very time consuming and not a convenient way to find a problem. Later, large vehicle scanners were made that could not leave a mechanic bay due to size. Then they started getting smaller and smaller. They still had very limited diagnostic use for a trained mechanic, but were needed for extended diagnostics.

Then the code reader was created. The code reader was about the size of a small book and would hook up to a diagnostic connector that was specific to one manufacturer only. The code reader would be used to test the vehicle engine only and get trouble codes output to a small screen. The code was used by a mechanic to do a pinpoint test using other tools before they repaired and retested the system to see if the code was gone. There was no other use except to retrieve the codes and no other information was given. With the advent of the OBD II system in 1996, the code reader got a generic connector that is used by all manufacturers. The code reader can still retrieve codes and clear codes.

With the OBD II system, manufacturers got more information that is given through the OBD connector. To access this information, a scan tool (scanner) can be used. A scanner can be very simple and only get basic information like engine codes and engine emission monitors, and also be able to clear codes. The scanner can also get very comprehensive with the ability to see live data input and outputs of the computer, access other systems data and codes like the anti-lock brakes, suspension, powertrain, body control, and air condition system. The scan tools today can even have reprogramming capabilities using manufacturer’s calibration files. However, not all scanners are the same as the more expensive ones have more functions. The manufacturers’ dealers will have scanners that have proprietary information that most aftermarket scanners have access to. This is so the dealer can have access to information like manufacturer specific codes and data, anti-theft systems, or other systems the manufacturer does not want the general public to have access too.

The bottom line is code readers can only retrieve codes and clear them, while scan tools can also test other systems and data usage to help diagnose problems better than just a code reader.