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Malfunction: a Skoda Euro 1.6 L car will automatically flameout when the coolant temperature starts at 50 C in winter. No matter when idling or driving, but if the engine is restarted after engine failure, the engine will not stop. Inspection and analysis: after taking over the car, the car is a heat engine, VAG1552 detection, no fault code storage; read data flow, are normal, and the engine work smoothly. The engine is extinguished to cool it naturally, and then connects the timing gun, the fuel injector test lamp, the VAG1552 and other equipment, and restarts the engine to monitor the injection, ignition and other data when the failure occurs. At first the engine runs normally, the fast idle speed is 1400r/min, and it decreases slowly with the temperature of the coolant. The ignition and fuel injection condition is good. The signal voltage of the oxygen sensor is 0.1 V, the injection pulse width is 5.2 MS, and the other data are also normal. But when the temperature of the coolant reaches about 55 C, it is found that the signal voltage of the oxygen sensor suddenly changed from 0.1 V to 1.l V, and the injection pulse width changed to 2 ms, and the engine began to tremble seriously, and the feeling would be flameout. The opening of the electronic throttle is also adjusted from 4 to 7 degrees, and a little carburetor cleaning agent is continued immediately to the inlet to maintain the engine operation (otherwise it will be extinguished), but the data of oxygen sensing and tut width remain unchanged. After about 1 min, the signal voltage of the oxygen sensor began to fluctuate slowly at 0.2 V-O.7 V, and everything returned to normal. The jet pulse width also changed to 4.2 MS, when the cooling temperature has been opened to 60 C, the oxygen sensing problem is suspected. To confirm this judgment, the engine is cooled again, and the 4 terminal of the oxygen sensor ends the connector to make the engine run in open loop mode and detect the oxygen sensor and its line. The voltage between the terminal 1 and terminal 2 of the guide side of the oxygen transmitter is 13 V, the voltage between terminal 3 and terminal 4 is 0.42 V, normal, the resistance of the oxygen sensor side terminal 1 and the Rui 2 is 35n, and the normal should be less than 20 n. It is also found that the engine is no longer flameout when the sensor side connector is disconnected, indicating that the flameout fault is indeed related to the oxygen sensor. Elimination method: replace oxygen sensor.