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Fault phenomenon: a Chevrolet 2.0L new track, has been running 1 03875km, the owner reflects the engine fault lights. Troubleshooting and Troubleshooting: using TECH2 to check engine control module set up a fault diagnosis code DTC P0133, that is, three element catalytic converter upstream oxygen sensor aging. The possible reasons for setting up DTC P01 33 fault codes are: (1) the fuel injection of the injector is too thin or too thick; (2) the oxygen sensor wire harness connector terminal influent; (3) the oxygen sensor wire harness is damaged; (4) the pressure of the fuel system is too low or too high; (5) the fuel is polluted (such as water); (6) the exhaust leakage near the heating oxygen sensor; and the engine vacuum Leak. The heated oxygen sensor (H02S) is used to monitor fuel control and three way catalytic converter. Each heating oxygen sensor compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. When the engine starts, the control module works in the "open loop" mode, ignoring the signal voltage of the heating oxygen sensor when calculating the air-fuel ratio. The control module provides a reference voltage or a bias voltage of about 450 rnV to the heated oxygen sensor. When the engine is running, the heated oxygen sensor is heated and starts to generate a voltage of 0 to 1000rnV. The voltage fluctuates up and down at the bias voltage. Once the control module has enough fluctuation in the voltage of the heating oxygen sensor, it enters the "closed loop" mode. The control module uses the temperature of the heating oxygen sensor to determine the air-fuel ratio. If the voltage of the heating oxygen sensor rises above the bias voltage (1 000mV), the fuel mixture is too thick; if the voltage of the heating type oxygen sensor is lower to the bias voltage (0mV), the fuel mixed steam is too thin. Each heating element inside the heated oxygen sensor heats the sensor, so that it rapidly preheat to the working temperature. This enables the system to enter the closed loop mode earlier and allow the control module to calculate the air-fuel ratio earlier. Looking at the oxygen sensor data in the engine data list, it is found that the change frequency of the signal voltage of the pre oxygen sensor is slow, and the car has been running 100000km, so it decides to change a new oxygen sensor, but the test car is not long to light the fault indicator and the fault is reproduced. Check the other data, in which the absolute pressure of the intake manifold is 28 ~ 29kPa while the normal value should be 30~31 kPa, and the long-term fuel adjustment value is 16%, and the normal value should be within 5%. Check the EGR valve opening and closing, three yuan catalytic converter is not blocked, the exhaust manifold pad and the exhaust manifold and the three element catalyst have no air leakage, and the rubber hose has been detected and cracked when the crankcase ventilation hose between the crankcase to the valve chamber cover is checked. Replace the crankcase ventilation PVC hose after data return to normal, troubleshooting.