Clean the throttle bloody.

If the idle speed of the engine is unstable, first of all, you should judge whether there is a fire, whether a cylinder of the engine has stalled, or whether it is not working well. 40,000 kilometers, if the throttle and nozzle are not cleaned, they should be cleaned. Then check the spark plug. Do you need to replace it? Generally, it needs to be replaced after 40 thousand kilometers. These should be the problems. Sensors are generally not easy to break down. If the sensor is broken, if you want to turn on the engine fault light, you can use the computer to see if there is any fault.