A Mercedes C200 car with a mileage of about 90 thousand km, a M111 engine and an automatic transmission, and a chassis model of W203. Users reflect: during the running of the vehicle, the engine fault lights occasionally light up, and the acceleration performance of the vehicle obviously decreases. After receiving the car: connect the diagnostic instrument for self diagnosis, the engine system has multiple fault codes, and the contents are related to the absence of cylinder ignition. Clear the trouble code, start the engine, and the engine fault lights go out. Replace spark plug, clean fuel injector, remove carbon deposit. On the road test, the fault appears again. The reason is estimated to be related to poor fuel quality. The modification of the fuel quality parameters is as follows: 1) select the control module matching menu and press the F3 key. .