Symptom: Jetta car jitter.
    Troubleshooting: the use of car detection equipment for diagnosis, display 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.
    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, is caused by other components of the 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 failure, replace the new oxygen sensor, 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 20-50. 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.