R Class ABS wheel speed problem

[Benjamin1]

Hi, hoping for any tips/advice/help please?
Enjoyed owning our 2011 R350Cdi for the past year.
Now the ABS light is on permanently (it was intermittent for a week or 2)
My iSoft code reader suggested L rear speed sensor defective- it was seized in port so I carefully drilled out/replaced. Now getting v brief intermittent drop out of speed reading (For a second or less) when I live view the data from the LH rear with assistant driving at 30mph. Hence ABS keeps switching off/yellow light back on dash and code: ‘Implausible wheel speed LH rear’
Changed the sensor again- same!
Not sure if this has a replaceable reluctor ring or not?
Is it likely to be this? Wiring? Abs unit?
cheers anyone! Ben

 

[mioba]

did you use a genuine sensor. Get the ring replaced. It also all needs to be cleaned inside.

 

[star]

Ring is part of bearing seal.

 

[LostKiwi]

They are very sensitive to depth. Just 1mm too far away from the seal and they won't work properly.
Also make sure the seal is clean.

 

[Uncle Benz]

If you’ve nibbed it with the drill it’ll be knackered

 

[Benjamin1]

Ring is part of bearing seal.

Thanks for replies- So does this mean whole driveshaft replacement?
would this be expected to give v intermittent drop out in wheel speed readings?
They were non- MB branded sensors, but is 2 with same problem likely? (I guess buying an MB one is one way to find out!)
The wiring is zip tied tight on suspension arm with a kink and wondered if that has been a prob for others in past?

 

[LostKiwi]

So does this mean whole driveshaft replacement?

No. It's the inner seal on the wheel bearing.

 

[bembo449]

id be tempted to take the sensor out and pear down the hole with a torch , twist the drive shaft to see if the ring is just spinning on the hub ?

 

[Benjamin1]

Thanks- will have another look in hole and try and clean.
sounds like next step could be hub off, get someone to press out bearing and refit new bearing with magnetic seal in correct orientation? Sounds relatively grim!
i remember changing reluctor rings on e class was fairly heavy going..

 

[BillyBoy]

Can you swap the sensors between sides to see if the fault moves across with it?

 

[mioba]

The reason I asked if original or not was because I replaced 2 on my w220 with non mercedes many years ago. They both died at about 12 months. Replaced with original and still going strong.

 

[Benjamin1]

Thanks.. I’ll have a look when stops raining