Mercedes Benz S350 engine fault lights

Super car mileage 240000km, auto diagnostic software configure the M272 engine Mercedes-Benz S350 sedan. Reflects the owner: The car engine fault lights.

Pick check the fault light lights, turn on diagnostic DAs are read engine fault code 0278: the right side of the intake camshaft adjustment solenoid valve (Y49 / 5) is shorted to ground, and storage; fault code 1208; along postponed direction continue to adjust the right the cylinder columns intake camshaft, and storage. Clear the fault code, the fault code still exists.

Guide the detection of fault code 0278 progress, activate camshaft adjustment solenoid valve (Y49 / 5), no reaction, possible causes and guide not to mention:

① may camshaft regulating solenoid valve Y49 / 5 are consuming too much damage.
② connected to the camshaft adjustment leads to the solenoid valve (Y49 / 5) eliminate short circuit or grounding.
(3) The engine control unit is damaged or internal short circuits.
④ extend auto diagnostic tool the engine chain or sprocket wear.
Maintenance, fault code 1208 guide columns intake camshaft pulse wheel to replace the right side of the cylinder.

After re-analysis fault code 0278, the first suspect camshaft regulating solenoid valve (Y49 / 5), an internal short circuit, the regulating solenoid valve due to the intake camshaft pulse wheel and the camshaft (Y49 / 5) is active and passive relationship. So replace it with a new camshaft adjustment solenoid valve, but the problem persists. View WIS by the circuit diagram (Figure 1) was informed that pin 1 on the engine control module N3/10 connected to the camshaft adjustment solenoid valve (Y49 / 5) 1 foot. Unplug the wires conduction auto code reader, measured with a multimeter and ground guide through. And four camshaft adjustment solenoid valve (Y49 / 4, Y49 / 5, Y49 / 6, Y49 / 7) shared a node Z7/38 If camshaft adjustment solenoid valve (Y49 / 5) to short-circuit, and there has been 3 camshaft adjustment solenoid valve should have been a short circuit fault, but the fact that the other three do not have this fault. From the above analysis that the engine diagnostic line will not be shorted to ground Secretary may only internal short circuit of the engine control module. Thus, the replacement of the engine diagnostic, programming, commissioning, fault code 0278 disappearance of this troubleshooting. Fault code 1208 is still there, and the replacement of a new engine control module fault code display 1206 (along postponed direction continued to adjust the right side of the cylinder columns intake camshaft). Analysis of the pulse wheel driven by the timing chain, reported this failure, there are two possibilities: first, like the diagnostic prompt blade fiscal sheep, may be the the camshaft pulse wheel damage; timing mechanism balance shaft sprocket wear. According to past experience, the balance the Lin-round wear, diagnostic guide failure will prompt the view cam lin round, but this car is only a guide to view the pulse wheel. So, first replace the right side of the intake camshaft pulse wheel installed commissioning, fault persists. Now only check 4 chain and balance shaft sprocket. Let go of the oil, and disassemble the oil pan and oil pan iron tablets, this point, the question should have been found, these iron particles is most likely due to the balance shaft sprocket wear.

To communicate with the owners of the engine opens, validation the camshaft sprocket indeed wear extremely serious, as shown in Figure 2.

The car after the owner's consent, and related components to replace the balance shaft and sprocket fault light is no longer lit, the engine is running properly, and troubleshooting.

So the array auto scanner summarize: during maintenance, diagnostic boot prompt to enhance analysis, will be detours encounter problems or in conjunction with diagnostic tips and repair experience, comprehensive analysis, from easy to difficult, step-by-step to solve.