| Along with automobile industry rapid development, our country like the other countries, facing more serious air pollution problem. Therefore, the great stricter emission regulations-Euro3 will implement soon all over China. The greatest different between Euro3 and the Euro2 emission regulations is introduce the On-Broad Diagnostics system.On-Board Diagnostic system must have the capability of identifying the likely area of malfunction by means of fault codes stored in computer memory. The Malfunction Indicator must active in the event of a malfunction of any emission-related component or system, at the same time, the malfunction information was stored in the computer memory. Diagnostic Trouble Codes and Freeze Frame can be read by scantool. Repairer can detect the malfunction quickly and repair the vehicle as soon as possible through the indication of Diagnostic Trouble Code.There are many monitors in OBD : catalyst efficiency monitor, oxygen sensor monitor, misfire monitor, EGR monitor, fuel system monitor, evaporative system monitor, secondary air system monitor, tank ventilation monitor, oxygen sensor heater monitor, positive crankcase ventilation system monitor, engine cooling system monitor, cold start emission reduction strategy monitor, variable valve timing and/or control system monitor and so on. While the monitor system detected malfunction, it would take some emergency procedures to make vehicle drive to maintenance station reluctantly.The type-approval of OBD has been introduced into vehicle type-approval procedures. The test of OBD system consists of the following items: oxygen sensor deterioration test, catalyst efficiency defective test, misfire test and electrical disconnection test of the electronic evaporative purge control device. The vehicle is approved if the Ml is activated and emissions can't exceed the limits of On-Board Diagnostic. The vehicle type which has obtained OBD certification, when satisfies the expansion condition may extend to other...
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