W221 Rear speed sensor/reluctor ring issue

[RoyRogers]

I've just had the usual ABS/ESP warning light & diagnostics said to check the rear right speed sensor.
After checking and replacing the sensor the fault remained so I purchased a new reluctor ring but before changing it I put it on my lathe and tested the new sensor with my multimeter and all seemed to be working +/- 40mv ac. After replacing the reluctor ring on the car I did the same test on the car and got no reading, took the car for a run (being hopeful) but ABS/ESP lit up again on the dash.
I'm not sure what i'm missing here and wondered if anyone else has had this issue.
Thanks in advance

 

[Botus]

on this model its recommended you change both sensors as a pair - they ALL die to time circa 9 years old

on mine the error message would not clear until I set a destination in the sat nav then it was all back to normal within 200 yards

 

[RoyRogers]

on this model its recommended you change both sensors as a pair - they ALL die to time circa 9 years old

on mine the error message would not clear until I set a destination in the sat nav then it was all back to normal within 200 yards

Thanks Botus
I'll give that a try. I've never had to replace both sides at the same time although probably a good idea.

 

[Botus]

yes only one fails but the Merc document on repair, specifies always replacing both at the same time.

 

[RoyRogers]

UPDATE
I purchased another sensor and after fitting, my diagnostics showed that I now had a fault on the left side. As I never had a problem before, I realised that the issue was with the sensors. I have now purchased 2 new sensors direct from Mercedes and all is working as it should. One new issue I had when both sensors were showing as faulty is that my steering went very heavy.

 

[Botus]

thanks for the update....