On Board Diagnostics



















ORIGINS OF OBD

The origins of OBD began back in 1982 when the California Air Resources Board (CARB) initiated regulations which would require all vehicles sold in California, starting in 1988, to have an on-board diagnostic system to detect emission failures. This system would later be referred to as OBD-I.

OBD-I was a simple ECU system that monitored various sensors and applied corrections to a map value based on engine conditions. This system revolutionized the auto repair industry by making it easy to identify faulty components, however, it provided no insight into the conditions that lead to the problem. Another drawback was non-existent standardization between different makes and models of vehicles and the availability of affordable scan tools for these proprietary systems.

With that in mind, the next generation OBD-II system was based on new standards starting in 1994 with a complete phase-in for California vehicles by 1996. Now, all vehicles must be OBD-II compliant and have a standardized 16-pin data link connector (DLC) with specific pins assignments, standardized communication protocols, standardized diagnostic trouble codes (DTC) and standardized terminology. Prior to 2008, five protocol types were in use; J1850-PWM, J1850-VPW, ISO 9141, KWP2000 and CAN. Starting in 2008, all vehicles sold in the US must now be CAN-BUS compliant.

Current OBD-II systems do more than just electrically check components for short or open circuits, OBD-II monitors any component that can have an effect on emissions by comparing the sensor output to an expected range. If malfunctioning or out-of-range, a diagnostic code number is stored which can only be read using a Code Reader or Scan Tool. Not all errors will cause the (MIL) "Malfunction Indicator Lamp" or "Check Engine Lamp" to illuminate. But if it does, this is a cause of concern to identify the problem before costly damage can occur. Sometimes, it can be something simple such as a loose or missing gas cap which caused an "Evaporative Emission Control" error.



SELECT YOUR VEHICLE FOR A LIST OF AVAILABLE TOOLS


ACURA


AUDI


BMW


BUICK


CADILLAC


CHEVROLET


CHRYSLER


DODGE


FORD


GEO


GMC


HONDA


HYUNDAI


INFINITI


ISUZU


JAGUAR


JEEP


KIA


LAND ROVER


LEXUS


MAZDA


MERCEDES


MERCURY


MINI


MITSUBISHI


NISSAN


OLDSMOBILE


PONTIAC


PORSCHE


SAAB


SATURN


SUBARU


SUZUKI


TOYOTA


VOLVO


VW













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Registered: January 25, 2000, Last Update: December 15, 2011