A Audi C5 A6 2.4L with a mileage of about 88 thousand km. The owner reflected that the car was easy to flameout during the running of the hot car and it was not easy to start after the fire. Fault reason: the activated carbon tank solenoid valve is in the normal open state, causing the mixture to be too thick. Fault analysis: the active carbon tank solenoid valve is part of the EVAP (fuel steam emission control system), which is controlled by ECU to adjust the vacuum degree of the vacuum chamber above the vacuum control valve, to change the opening of the vacuum control valve, and to control the amount of gasoline vapor in the intake intake pipe. ECU controls the electricity or power of the solenoid valve according to the throttle position sensor, the coolant temperature sensor and the intake temperature sensor signal, and the solenoid valve controls the suction channel between the activated carbon tank and the intake pipe. When the engine is idle (less intake) or lower temperature, the ECU makes the solenoid valve cut off and closes the suction channel. The fuel vapor in the activated carbon tank can not be inhaled into the intake pipe, in order to prevent the excessive fuel vapor entry causing the deterioration of the combustion quality.