The OBD II (On-Board Diagnostic II) standard, introduced in the USA in 1996 and which became a global standard from 2000, imposes an obligation on manufacturers to create on-board diagnostic systems for all passenger cars and light commercial vehicles. A mandatory function of these systems is the measurement and continuous monitoring of basic powertrain parameters, including all emission-critical parameters, i.e., those that directly or indirectly indicate the possibility of increased emissions from the exhaust system or fuel supply system.The purpose of using OBD II is to eliminate off-board measurement and diagnostic systems and replace them with a single, unified on-board system that can be used to control and diagnose the powertrain, and ultimately the entire vehicle. The use of the OBD II system (called EOBD – European On-Board Diagnostic in Europe) in a passenger car means equipping the vehicle with a standard set of sensors, devices, and control units that ensure compliance with OBD II standards and regulations regarding environmental pollution. The primary feature of the OBD II standard that enables its widespread acceptance and application is a level of standardization requirements unprecedented in the automotive industry.
1. The concept of the technical condition of vehicles
The necessity of assessing the technical condition of an object arises from the need to make decisions regarding the “quality” and further handling of the object. This may be a decision about its use, undertaking preventive measures (adjustments, replacement of components or entire assemblies), or introducing changes in design, technology, or operation.
The number of states in which a machine can be found results from its structural and functional design. For a non-decomposed machine, one can distinguish states (…)
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Source: Logistyka Magazine 6/2011
On-board diagnostic system for motor vehicles – PDF file for download