Fault check
    Asked the owner, this car has been overhauled in other garage. Maintenance, the use of car detection diagnostic equipment for diagnosis, indicating that this car aerobic sensor fault code exists, the other sensors, actuators work well. After replacing the oxygen sensor, with the diagnostic instrument clear code, found that the fault code still exists, can not be cleared. The fault still exists.
    Failure analysis
    For the existence of aerobic sensor fault, and the fault code can not afford to clear this phenomenon analysis, suspected failure is not in the oxygen sensor, but in other components, other components caused by oxygen sensor failure phenomenon. Because the oxygen sensor in the car work process, if the engine is not working properly, the emission exhaust gas detection of CO, HC, NOX content will change, resulting in changes in oxygen ion concentration. Oxygen sensor at work, the other components of the failure of the endorsement elements, that is, when the oxygen sensor failure, the fault is not necessarily in the oxygen sensor itself, there may be other components of poor work, so that the emission content changes, causing The presence of this fault code. If the oxygen sensor fails, replace the new oxygen sensor (the oxygen sensor should be good), the fault should be excluded. So the problem may not be in the oxygen sensor itself.
    In the future detection and diagnosis, the other sensors, actuators for further inspection and analysis. With the instrument for data flow analysis and found that the engine in the course of work, the data flow shows the throttle controller when the throttle valve opening degree of 80, and the oxygen sensor signal voltage is high, air-fuel ratio is too thick. According to common sense analysis, the engine idling, the normal throttle opening should be 20 to 50. This does not mean that the oxygen sensor itself must have a problem, so the problem is focused on the throttle controller.
    After careful examination found throttle controller dirty, cleaning throttle controller, troubleshooting. The engine works for a while after checking the engine, no fault code exists. Replace the old oxygen sensor, the work is still good.
    Fault summary
    Oxygen sensor detects the composition of the engine exhaust gas product. When the oxygen sensor has a fault code, it may be the fault of the oxygen sensor itself. However, if the oxygen sensor itself is good, the fault should be related to the other Aspects of analysis. Because the idle time, the throttle opening increases, the engine will enter the computer ECU a current throttle opening of the actual signal voltage, idling high, the computer ECU according to the size of the current throttle opening control fuel injection. Throttle controller dirty, the actual gas supply than the previous throttle opening under the theoretical intake of less, corresponding to the current situation of the engine air-fuel relatively thick, the engine emissions are not up to standard. When the oxygen sensor detects this emissions, the computer ECU mistakenly believe that the oxygen sensor itself has failed, the oxygen sensor fault code exists inside the computer, so that we from the surface phenomenon is the oxygen sensor itself is a problem, so misuse Oxygen sensor.