A Mercedes S320 car with a mileage of about 80 thousand km, a M112 engine and an automatic transmission, and a chassis model of W220. Users reflect: during the driving process, the engine suddenly failed to accelerate, the idling speed was serious, and the engine failure lamp of the dashboard lit up. After taking the car: self diagnosis, the engine system has multiple fault codes, the contents are as follows: "P201F9 3 cylinder injector (Y62y3) has fault"; "P2050, the cylinder fire caused three yuan catalytic converter damage"; "P20539 3 cylinder fire cause three yuan catalytic converter damage". Check the cylinder running stability data, the 3 cylinder data reached 10.84, indicating that the cylinder has not been working at all. Measurement of the 3 cylinder injector resistance is infinite, indicating that the internal winding circuit. Replace the 3 cylinder injector, the fault is completely eliminated. There are three common reasons for the ignition loss, one is the bad ignition system, the two is the bad work of the fuel injection system, and the three is the poor working of the engine parts (such as the valve seat damage, the valve spring performance, the air intake manifold leakage, etc.). During maintenance, we usually use the method of removing fuel injector wiring harness plug or ignition coil harness plug, and so on, that is, broken cylinder detection method. After finding fault components, the replacement process can be completely eliminated.