RomRaider

Hello all,
I have been in pain chasing camshaft sensor problems on my car and the BMW ones are currently backordered with no ETA. Siemens one lasted 1.5 years, Hella lasted 6 month, second Hella 4 days.

Question: has anyone figure out the failure mode of them and why the aftermarket ones don't work?

So far what I know:
It is a sensor type called Eddy Current Speed sensor, they can measure any conductive tooth but doesn't have to be magnetic. MS41 sends a 2.5V AC voltage to it (120 kHz), then it acts as a transformer and transmits to the secondary coil, when a tooth comes close the induced magnetic field change created a phase shift and DME uses this to decide that its at TDC.

I have 3 failure theories:
1. Iron core becomes magnetized
-Stock failed measured at 70uT, Hella (new and "failed") 50uT, stock after a demagnetizer at 60uT. Have not put the demagnetized back in to try yet.
-Maybe stock one is better metal that resists this?
2. The coil wire burns out from too much current
3. The DME has some sort of oscillator failure (or a trim capacitor) and becomes super sensitive to noise (but why so sensitive to aftermarket sensors?)

I am debating just using a hall sensor with some kind of phase shift circuit and put it in the DME. But really want to know why they are so temperamental. I'll try scoping it at work and see what it says.

Anyone explored this in detail?

I'm curious about this solution as well. I am digging into fixing this issue one my S52B32 and MS41. I have non-oem sensor that is functioning, but for how long?