S211 e270 cdi abs & esp defective

[b21playa]

Hi all

Purchased the above as a bit of a gamble. Starts fine, goes into drive but stays in 1 gear.

Fault codes point to both rear abs sensors which I've ordered new ones for.

How common is it for both to go at the same time?
Could it be the ruluctor rings on the driveshaft?

Thanks in advance