[marco_polo]

Yes, the front has sensors too, they're more reliable as a rule. Twenny changed a faulty front on his old E82 fairly recently.

Definitely no rear bright spots on the rings / witnesses of contact?

 

[marco_polo]

It's quit a dull silver and there's about a inch area that looks shiny silver ( like new almost)

This is on this drivers side.

95% sure that's your issue, a witness it's been rubbing.

 

[marco_polo]

How worn does the tip of the sensor look?

You could try to bodge it with a thin washer/spacer, see if that gets you going?

 

[marco_polo]

The wheel speed sensor is used for the speedo, ABS, Traction Control and TPMS (compares how fast each wheel is turning - if one suddenly starts rotating faster than the others the car assumes it's suddenly got a smaller radius, ie, flat tyre.)

 

[marco_polo]

Yup, get a 2nd opinion (or 3) from independant BMW specialists, they will have seen a few of these by now.

 

[marco_polo]

Rings should cost you about £10, but there would be slightly more labour involved.