History Today's automobile is a complex machine. Thanks to advanced features like anti-lock brakes, computerized climate control and entertainment systems, hybrid engines, and ever-tightening emissions restrictions, a modern car can contain thousands of parts and miles of wire. When one of these components malfunctions, how can the modern home troubleshooter ever hope to track down the problem? Traditional "pull a plug wire to check for a spark" troubleshooting techniques are no longer effective --in fact, this simple act can be enough to damage the electronics on many modern cars.
As cars' complexity increased, auto manufacturers began integrating on-board diagnostic (OBD) systems, which continuously monitor the vehicle's functions. For example, if an engine occasionally misfires on one cylinder or the oxygen sensor malfunctions, an error code will be generated and stored on the car's computer. If the problem is serious enough, the "check engine" light comes on, letting the driver know that it's time for a repair.
Eventually, on-board diagnostic systems were consolidated under a single set of standards (known as OBD II). Starting in 1996, all cars and light trucks sold in the US were required to adhere to the OBD II standard.
NOTE: Starting in 2008, a new standard called "CAN" will become mandatory for all vehicles, and some auto manufacturers are already producing CAN-compliant vehicles. OBD II code readers may or may not work with CAN vehicles -- check the product detail page to check if the scanner works with OBD II, CAN, or both. Some scanners also work with the older OBD-I standard (for some vehicles from the mid-'80s thru 1995) or other manufacturer-specific formats.
Initially, the devices used by mechanics to communicate with cars' on-board computers were huge and expensive. These days, however, they're small enough to fit in a toolbox and start at less than $100, making a portable OBD II code reader a "must-have" tool for the modern home mechanic.
Features Three popular players in the handheld scanner market are Actron, AutoXray, and Equus. Each manufacturer has a number of models ranging from simple and inexpensive devices to deluxe, complex units. Every device will read codes from OBD-II autos and reset the "check engine" light; advanced models feature more informative screens, battery power to store codes after the unit is unplugged, and broader compatibility with earlier OBD-I vehicles or new CAN vehicles. "Code Readers" pull codes from the car's on-board computers, while "Scanners" also monitor vehicle data from a vehicle's sensors in realtime.
Actron Actron's lineup begins with the Actron CP9125 PocketScan Code Reader, a simple and inexpensive reader. This tool displays a code like "P0130" on its LCD screen, and the user then looks up the code online or in the book that comes with the code reader. In this specific example, "P0130" indicates a malfunctioning oxygen sensor circuit.
AutoXray AutoXray's lineup starts with the AutoXray EZ-Read 1000 Code Reader, which works with both OBD-II and CAN vehicles, displays fault codes and descriptions on the display, can be updated, and comes with a carrying case. The AutoXray EZ-Read 2000 Advanced Code Reader is similar, but adds support for earlier OBD-I vehicles.
The AutoXray AX1500 CodeScout features an updated design with a multi-line display and battery power.
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is a true scanner, and the AutoXray EZ-Scan 5000 Scanner adds OBD-I support. The AutoXray 6000 EZ-Scan Scanner has all the features of the 5000, plus enhanced OBD-II support for GM, Ford, and Toyota.
Equus The INNOVA 3030 Diagnostic Code Reader for OBDII Vehicles, Equus' entry-level scanner, is compatible with both OBD-II and CAN systems and includes status LEDs that quickly let you know if your vehicle will pass its emissions test.
The INNOVA 3100 CAN/OBDII Code Reader adds battery back-up and its firmware can be upgraded from your PC using the included USB cable. The "C" in its title shows it's CAN compatible -- the older 3100 is OBDII compatible, but not CAN compatible.
The Equus 3110 Innova Diagnostic Code Scanner with Freeze Frame Data for OBDII Vehicles is the top-of-the-line offering from Equus. In addition to the 3100C's features, the 3110 includes a multi-line display (to show the trouble codes and their definitions on screen), and also acts as a scanner to store and display freeze-frame data from the car.
