What matters to the majority of DIYer's, as well as the clients who patronize my dealership, is that the car is fixed. Failure analysis is best left to the manufacturer/engineers. That's what they get paid for.


Concerning your original statement, "We need to define " bad " .. Have the magnets lost magnetism or are they swelling.......", I don't know how any technician would be able to determine this. I've had quite a bit of MB technical training over the course of my career, but I've never been trained how to determine "magnetism" performance!


FWIW, the issue with the cam solenoids (as I've been told by MBUSA), has to do with manufacturing tolerances/hardening of the magnetically actuated plungers inside the solenoids. Movement of the plunger either directs or restricts oil pressure flow within the cam timing device. Over time the plunger surface can become scored, eventually resulting in the plunger becoming sluggish, or completely stuck. When this happens the cam position sensors report the data to the engine management system (ME 9.7). Once ME 9.7 determines one or more camshafts out-of-position via mapping software/logic chain, a fault code is set.

All this tech-talk might be interesting to kick around on the Forum, but IMHO it doesn't really help fix the car.