The mileage is about 50 thousand km, with a 217 engine and a chassis E200 of 212 Mercedes Benz. Users reflect: after the car has stopped for a period of time, the engine is occasionally difficult to start, and the engine room after the start of the "carbazaka" noise, about 1 min after the noise automatically disappear. Fault diagnosis: after commissioning, several times after starting the engine, there is no fault phenomenon that is difficult to start. A special fault detector XENTRY is used to detect the engine system. The fault code "P0017 6 2 - exhaust camshaft (1 cylinder column)" is not reliable compared with the position of the crankshaft, and the signal ratio has a fault ". The possible reasons for the analysis of the fault code are: exhaust camshaft position sensor and crankshaft position sensor damage or installation error; exhaust camshaft position sensor and crankshaft position sensor line or engine control unit fault; valve timing error; camshaft adjusting the electromagnetic valve or camshaft regulator fault. When the engine room cover is opened, the installation position of the position sensor of the camshaft and the position sensor of the crankshaft is checked first. According to the circuit in the WIS, the circuit of the position sensor of the camshaft and the position sensor of the crankshaft leads to the control unit of the engine, and the short circuit, the circuit breaker and the virtual connection are not found. The displacement camshaft position sensor is suspected to be damaged, the intake camshaft position sensor and the exhaust camshaft position sensor are replaced after the installation of the test car. The engine starts 2 times before starting the engine, and the engine room sends out the "carbazar" noise, and the stethoscope is used to find the different noise parts, and the abnormal noise is found from the valve chamber cover. The position of the right front exhaust camshaft adjuster gives rise to the damage of the exhaust camshaft adjuster. After removing the valve cover and the front cover of the engine, it is found that the reset spring of the exhaust camshaft adjuster is stuck, and the shell is seriously worn. Mark the timing mark of camshaft and crankshaft, remove the exhaust camshaft regulator and decompose, and find that the locking pin hole of exhaust camshaft adjuster is worn seriously. Troubleshooting: after replacement of exhaust camshaft adjuster, trial run, troubleshooting thoroughly. Fault analysis: the adjustment function of the camshaft regulator is controlled by the oil pressure and the camshaft regulating valve. When the camshaft adjusts the solenoid valve, it controls the contact between the camshaft regulator and the camshaft regulator and adjusts the angle of advance angle and delay of the camshaft under the action of oil pressure; when the camshaft adjusts the electricity, the camshaft adjusts the electricity. When the magnetic valve is not triggered, the camshaft regulator lock pin locks it in the basic position to prevent the camshaft regulator from participating in the engine when the engine is starting or the part of the load is not required. The fault is caused by the serious wear of the locking pin hole of the camshaft adjuster and can not be locked in the basic position.