Front left wheel rpm is intermittent - ABS unavailable

Hi all,

I have a 2008 ML320 (164.122), were ABS/ESP says it is not available. I already replaced ALL rpm sensors, but front left wheel is still strange.
I have a iCarsoft scanner, and if I read ESP -> running values -> rpm sensors, I can see that all four report speed, *but* front left speed is strange, goes up and down as the wheel turns, while the other three wheels show a 'constant' speed. I have done the test at multiple speeds, from 10km/h to 40km/h.

If I reset the errors in ABS/ESP, and start driving the car, the front right wheel brakes get engaged like crazy, kind of expected, as ESP sees left wheel "stopping".

Currently, I am thinking that the magnetic ring might have some damage. The car was bought used 2 years ago, and was until one month ago that the ABS/ESP & front wheel problems started. I also discovered that it had a frontal collision of some type, cause I discovered a few mis placed/ broken parts while changing the rpm front sensors. Has anyone seen something like this before? I know that the wheel bearing comes with the magnetic ring.

Any suggestions?

I already read the thread " ML320 CDI ongoing self braking problem??? ", but does not look like my problem.


Thanks.