Feature: 1. OE Number: The referencing OE number of this ECU engine control module is A2721535291, which is molded and designed depend on the original data. 2. Fitment: The engine control module unit is a replacement for Benz W212 W221 E300 E350 S450 S550, please check the model of your vehicle before ordering. 3. Durable Construction: Constructed with a durable aluminum alloy shell and precision welded internal circuit board, robust design effectively prevents vibration and wear, ensuring stable operation. 4. High Performance and Efficiency: The ECU engine control module manages and coordinates your engine's systems for optimum performance and efficiency, ensures your vehicle runs smoothly while maximizing fuel economy. 5. Professional Installation Required: Please note, this control unit is not a plug and play device. Re programming and re coding are necessary for proper installation and functioning. Specification: Item Type: ECU Engine Control ModuleOE Number: A2721535291 .Material: Aluminum alloy + ABSFitment:Replacement for Benz W212 W221 E300 E350 S450 S550 Functions And Applications Of Engine Panel Ecus: 1. Control the working state of the engine: The engine computer board is the core equipment of engine control, which analyzes and controls the engine by receiving the signals from the sensors to achieve better fuel economy, reduce emissions and protect the engine; 2. Strong protection and anti interference ability: The engine computer board adopts precise hardware components and efficient software algorithms, which has strong anti interference ability and high reliability, and can work normally in harsh working environments; 3. Complete functions and strong scalability: The engine computer board has rich functions and interfaces, which can communicate and integrate with other vehicle systems (such as transmission, ABS, in vehicle entertainment system, etc.) to realize the intelligent control of the vehicle; Installation Precautions: 1. It is recommended to find a professional auto repair engineer to install, and the computer board needs to be programmed before installation 2. When installing the product, pay attention to check out the cause of the previous damage to the computer board to avoid damaging the computer board again due to the same failure; 3. Check whether the voltage is normal (voltage about 12V) before installing the computer board, it is recommended not to install it above 15V, check whether the wiring is normal, and whether the iron is good, otherwise there is a possibility of damage to the computer board; 4. After installing the computer board (insert the plug for trial operation), open the key to the NO position, switch back and forth three or four times, and then start again. 5. If the vehicle has an anti theft function, it needs to be decoded (matched) before it can be installed, which will depend on your car and not on the computer board Correct Installation Method Of Computer Board: 1. First remove a live wire from the battery cable, then install the computer board (circuit board), and then connect the battery wire. 2. Put the car key on the NO and do not get on the car, wait for 1 2 minutes before igniting. 3. If it doesn't ignite last time, repeat the previous step, or check whether there is dust in the plug of the computer board, if there is any, you can clean it with a clean brush, or check whether the pins are neat, so that the computer board is basically OK to install Solutions to common faults: 1. The fault light is on, indicating that there is a problem with the sensor. 2. If you repeatedly burn the computer board "ECU" or can't refuel, please check whether the generator voltage is normal. 3. If there is a lack of cylinder, check whether the spark plug, ignition wire, fuel injector, etc. are normal. 4. If the idle speed is unstable, please check whether the idle motor and throttle valve body are normal and have foreign objects. 5. If there is difficulty in starting, please check whether the pressure sensor and water temperature sensor are normal. 6. If it cannot be started, please check whether the crankshaft position sensor "Speed Sensor" is normal. Board Basics: 1. Product installation: confirm that the product model and specifications match, install and fix the new circuit board, connect the wiring harness connector, and repeatedly switch the ignition switch 3 5 times "switch time 2 3 wonder, closing time 4 6 wonder" 2 Check and judge after installing the computer board: 1) Whether the idle speed is running normally "800 950 rpm of the heat engine, 1000 1300 rpm of the cold engine", 2) Whether the electronic fan is running normally "85°C on, 90°C off", 3) Whether the air conditioner is running normally "increase the idle speed to 1100 1300 rpm", 4) Whet