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A80 Pro Intelligent Diagnosis System
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Chapter IV Additional Information
1. Description of OBDII and the function of sensor components
1.1 OBDII function description
In 1994, the American Society of Automotive Engineers proposed the second generation of
self-diagnosis system for on-board faults, namely OBD-II. OBD-II unifies the form of the fault
detection socket, the number and meaning of the fault code, and the reading method of the fault code,
and adds a strong data stream detection function. However, the fault code and data flow can only be
obtained with the microcomputer fault detector, and the fault code cannot be read manually. So far,
after the 1996 production of vehicles in the United States, the introduction of vehicles produced by
American technology (such as Shanghai Buick, etc.) and vehicles sold to the United States, only
OBD-II has been adopted, and OBD-I has been completely abandoned, other vehicles are generally
OBD-I and OBD-II coexist.
Electronic technology is applied to the engine management system. In addition to basic functions
such as fuel injection and ignition functions, as well as on-board (OBD) function. When the system
fails, the fault light (MIL) or the check engine warning light (Check Engine) lights up. At the same
time, the powertrain control module (PCM) stores the fault information in the memory, and the fault
code can be read out from the PCM through a certain program. According to the prompt of the fault
code, you can quickly and accurately determine the nature and location of the fault, and then
specifically check the relevant parts, components and lines to eliminate the faults.
OBD II set standards. The main points of the standard are as follows：
（1）Standardized 16-pin diagnostic seats (DLC)
（2）Standardized electronic protocols
（3）Standardized diagnostic codes (DTC)
（4）Standardized technology
The OBD II system is technologically advanced and very effective in detecting emissions problems,
but OBD II is powerless to warn drivers of whether to accept MIL warnings. To this end, OBD III
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