Both of these tools have their strengths and weaknesses. Both types will connect to the vehicles’ OBD II port. Both will read codes. Both will clear codes. This is where the two start to differ.

Code Readers were intentionally designed to perform two functions. Read the current codes and clear the codes. Depending on the tool it may offer a generic code description. They are very quick and easy to operate. The learning curve is very easy. This is about the limit of their capability.

Be aware there are some very serious drawbacks to using a Code Reader as a diagnostic tool. You do not know what "Diagnostic Monitors" have completed successfully or which ones failed. You do not know the "Freeze Frame" data. Both of these are needed to diagnose and duplicate the conditions for post repair confirmation.

If you understand that a code is nothing more than an indication of a failure area and requires more investigative work to find the parent problem before just replacing parts and possibly spending money unnecessarily then you will want to own a scan tool. Statistics from many state Environmental Protection Departments show 20% of post repair emissions failures fail a second time.

Scan Tools can read codes (current, pending and permanent), read "Freeze Frame" data, display the data the PCM is transmitting, read the VIN of the vehicle, read the part numbers of the PCM, read conflict data, access the different PCMs, read the monitor states, live graph sensor data, and more. They are quick to connect with the PCM.

Scan Tools come in two versions; the Generic Data capable and the Enhanced Data capable. The Generic Data Scan Tool can be used to diagnose and repair about 80% of the vehicles. The other 20% of repairs need an Enhanced Data Scan Tool plus other specialty diagnostic tools as the problems may be intermittent or require bidirectional control.

Generic Scan Tools usually do not have bidirectional control for pin point testing. The Generic Scan Tools come in several formats; one is the handheld scan tool that typically sells from $99 to several hundred dollars. Many of these handhelds are updateable with a subscription via the internet. This is both a blessing and a curse, as these scan tools could become infected with a virus that could be transmitted to the vehicle. Also this subscription model does increase the cost to own.

The laptop enabled Scan Tool starts under $50 for a good quality tool. They can connect to all OBD II protocols from 1996 to current. Some tools are flash upgradeable to add function. Most are based on an 8 bit program chip. The two largest suppliers of the chips are Micro Electronics and ELM electronics. Micro Electronics is the largest manufacturer and offers more chips with more function capable. ELM is the better known name. There are some cloned chip tools that are cheaper, but quality can be an issue.

There have been reported problems of some scan tools not connecting to vehicles. This happens even with the OEM Enhanced Data scan tools (EG: Tech II). Usually the tool gets blamed, but it rarely is the tool. It usually is the car’s programming and some auto manufacturers instead of fixing the problem code decided to call the foul up a "feature".

Laptop Scan Tools are only limited by the software program. Some are free. The better ones for more professional usage start around $70. Since these scan tools are powered by a laptop, with adequate anti virus protection the probability of infecting a vehicle diminishes. Two of the better ones for the Micro and ELM chip tools are ScanMaster by WG Soft and OBD 2007 by GLM Software. WG Software offers a demo version but it’s severely crippled and doesn’t show the quality of the program. GLM Software offers a fully functional two week trial. Recently they added a free version called "Lite" that retains many of the OBD 2007 capabilities. Software packages will be discussed in a later article.

As you can see these generic data scan tools are a great investment and every mechanic and enthusiast should have one of these in their toolbox even if they own an enhanced data scan tool. In the next article we will discuss the many enhanced data scan tools and present information about the software packages, cost, etc.

Copyright © 2011 JD Durham