The mileage is about 126 thousand km, with a 211 chassis Mercedes Benz E280. Recently, the KG button to operate the left front door handle of the car is unable to lock and unlock the vehicle, and the KG button system operating on the other door handles is normal. Fault diagnosis: connecting the DAS diagnostic instrument to the fast test of the vehicle, the result shows that the KG system has no fault storage, and the analysis should be the cause of the mechanical failure of the component leading to the failure of the KG function of the left front door. Then use the DAS diagnostic instrument into the EIS unit KG part "Actual values" (actual value) option, select the "door handle" (door handle) submenu, by matching the operation of the door handle "push" (push) and the "pull" (pull) button to observe the actual value of the button switch is not changed. After testing, it is found that "door handle" "push" (push) and "pull" (pull) value sometimes have adhesion state, which is abnormal, and the left front door pull hand is replaced after the replacement. The left front door handle and the left rear door handle are different, although the part numbers are different, but in special circumstances, they can be replaced when they are repaired to help diagnose. Fault summary: the KG main control unit of the 211E class car and the 219 CLS Coupe is the EIS electronic ignition switch, which is very different from other models. The KG system control principle of the KG system is basically the same as that of the ML350 model, the KG control module of the R class is located under the spare spare part of the trunk, and the KG control module should be first checked to see if the KG control module is flooded. Due to the particularity of its position, the KG failure phenomenon caused by the influent of the KG control module has been dealt with. The unspoonful boot button of the vehicle will be replaced after pulling out, which will cause the function failure of the engine without the spoon. At this time, the synchronization operation is needed. The specific method is to put the button in place and take out the key out of the car. A remote control locking and unlocking operation can be carried out on the vehicle.