A mileage of about 110 thousand km, the model 211 is the Mercedes Benz C200, which carries 642 diesel engines in 2008. The user showed that the car was powerless and the engine fault light was on. Inspection and analysis: maintenance personnel test engine control unit, found fault code P2510---- engine pressurization is insufficient. The turbocharger's supercharger Y77/1 is individually tested by the fault diagnosis instrument, and the result is normal. This shows that the problem is not the regulation of the air pressure, but the output pressure of the supercharger is fundamentally inadequate. A barometer is installed between the exhaust manifold and the intake port of the turbocharger. Start the engine, make it idle, and turn off all the electrical equipment on the vehicle. Use the fault diagnosis device to control the closing of the EGR valve and then increase the engine speed to 2000 r/min. The exhaust backpressure at the front of the turbocharger is 205 kPa and 105 kPa above the atmospheric pressure, which means that the supercharger can get enough intensity of the exhaust air flow. Under such circumstances, the problem of supercharging can only be the problem of the supercharger itself. Troubleshooting: replacement of turbocharger and troubleshooting.