An Overview of On-Board Diagnostics

What is OBD?
  OBD or On-Board Diagnostics as a generic term refers to the self-diagnostic and reporting capability of a vehicle. This function gives the technician an immediate access to information on the state of health of different sub-systems within the vehicle.

Origin of OBD

The state of California, to combat the smog problems in LA, started requiring emission control systems on all 1966 model cars. It was in 1968 that the federal government made these controls nationwide. Thus, finally, a Clean Air Act was passed by the congress in 1970 and an Environmental Protections Agency (EPA) was established. This started a series of emission standards and requirements for maintenance of vehicles for extended periods of time.

Only electronically controlled systems can meet these top notch standards. Sensors are measure and adjust engine performance in order to provide the minimum possible pollution. These sensors were also helpful in providing early diagnostic assistance.

Evolution of OBD

OBD, since its inception in the early 1980s, has undergone varied levels of sophistications in terms of the amount of diagnostic information available. Early instances of OBD would simply indicate malfunctions using light indicators also referred to as MILs (Malfunction Indicator Light) but would not provide any further detailed information on the nature of the problem.

Modern OBD models use a standardized fast digital communications port to provide real-time data along with standardized series of diagnostic trouble codes (DTCs) which allow the technicians to identify malfunctions within a vehicle and arrange remedies in a jiffy.

OBD Standards

The Environmental Protection Agency is responsible for reducing mobile emissions from trucks and cars. The EPA can require manufacturers to build cars that meet the strictest emissions standards. While OBD–I could just be used for emission control systems that did not have a specified standards, OBD–II provides a universal inspection and diagnosis method to be sure the car is performing to OEM (Original Equipment Manufacturer) standards.

Types of OBD

OBD–I: The basic intent of OBD–I was to enable and encourage automobile manufacturers to design reliable emission control systems that could remain effective throughout the vehicles usable life.

OBD–II: This is an improvement over OBD–I in both capability and standardization. The OBD standard mainly gives 3 specifications. They include the diagnostic connector type and its pinout, the messaging format, and available electrical signalling protocols. It also provides a candidate list of vehicle parameters to monitor along with how to encode the data for each.

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