SINCE 2004--Professional Auto Diagnostic Factory

Understanding Codes and Scan Tool Trends

Understanding Codes

Regardless of what type of code reader or scan tool is used to read codes, an important point to remember is that a code by itself is not a diagnosis. It is a starting point for further testing and diagnosis. The code may tell you the nature of the problem or the circuit that is acting up, but it doesn’t tell you what’s causing it. This is why you can’t necessarily sell a part based on the code that was pulled from a vehicle.

The “enable criteria” that sets a code will vary from one vehicle to another, so there are no rules of thumb to guide your diagnosis. You usually need the OEM service information, diagnostic charts, and test specifications to isolate the fault. You also need additional test equipment such as a digital multimeter (possibly a graphing multimeter), digital storage oscilloscope and/or five-gas emissions analyzer to accurately diagnose some driveability and emissions problems — plus a thorough understanding of engine control systems, sensors and onboard diagnostics. In other words, the motorist really should take his or her vehicle to a professional shop.

Some higher-end scan tools not only display codes and data, but can also graph sensor waveforms. The ability to graph data makes it easier to see what is actually going on and to compare data.

Scan Tool Trends

In recent years, more and more new diagnostic tools have been introduced from companies such Actron (OTC), Auterra, Autologic, AutoXray (OTC), Baum Tools, Delphi and others. Their products range from entry level code readers to professional grade scan tools that combine scan tool, graphing and emissions functions all in one. Competition is driving down prices and forcing scan tool suppliers to include more features at little or no extra cost. This includes larger displays, color graphics, broader vehicle make and model applications (though European coverage is still limited in most tools to generic OBD II compliant only) and more parameter identification data. This is good news because it means scan tool users get more for their money.

Menus have also improved, making the tools much easier to use. Larger screens and color graphics also make it easier to see the data even in bright sunlight. Good visibility reduces the risk of misreading information and is a plus for aging boomers whose eyes may not be as sharp as they were 20 years ago.

Another trend we’re seeing is the narrowing gap between OEM dealer scan tools and aftermarket scan tools. A gap still exists and some aftermarket versions of the OEM scan tool have been “decontented”, but other aftermarket scan tools now offer most if not all of the diagnostic capabilities of the factory scan tool.

Most professional technicians say the factory OEM scan tools are the best, but can’t afford to own a different scan tool for each and every make of vehicle they work on. So they may have one or two OEM scan tools for the more common makes they service, and an aftermarket “all makes and models” scan tool for the rest.

Finally, there is the issue of tool obsolescence. Most scan tools are upgradeable with a plug-in cartridge, memory card or with software downloads. The tool manufacturer may offer free upgrades for a certain period of time, or they may charge an arm and a leg for annual updates. These are important things that need to be considered before a tool is purchased.