The original on-board diagnostics (OBD I) refers to most cars manufactured 1981 - 1995. Unfortunately, due to no clear set of standards for OBD I cars, there are different ways used to communicate and interface with the car's computer, which allowed for multiple interpretations amongst vehicle manufacturers. All you have to do is choose the correct adapter cable. Details on adapter cables may be found in "What are DLCs?"

Beginning in 1996, all passenger cars and light trucks (8,500 lbs. GVW or less) built for sale in the U.S. were required to be OBD II-compliant. In California, the GVW limit is 14,000 lbs. GWV stands for Gross Vehicle Weight. This information usually can be found on a sticker located on the driver's doorframe.

Vehicles over 8500 lbs (14,000 lbs. California) are considered heavy duty and are exempt from the requirement to be OBD II compliant. Usually a scanner from the manufacturer or from a higher end tool company is required in order to interface with heavy-duty vehicles.
Although some 1994 & 1995 vehicles are OBD II-compliant, no OBD II vehicles were manufactured before 1994.

Here are three ways to determine if your vehicle is OBD II equipped:

1. All OBD II cars and light trucks will have a 16-pin "D" shaped diagnostic connector. If your connector has fewer pins, don't worry. Manufacturers are not required to use all 16 pins and they can use them as they see fit. It should be located on the driver's side, under the dash near the steering wheel. Connector placement may vary slightly depending on the manufacturer. Please Note: Some 1994 & 1995 vehicles (most notably GM) may be equipped with the OBD II 16 pin connector but are not OBD II compliant. For these vehicles, be sure to check the VECI decal as outlined in #2 below.


2. Refer to the Vehicle Emissions Control Information Decal that is located in the engine compartment.


3. Refer to the manufacturer's certified service manual containing emissions information.

All AutoXray Scan Tools and Code Readers are OBD-II compatible.