ABS Sensor Issue

After finally getting my rear calipers off ,I was originally faced with 2 issues ( however maybe only 1 after some checking of the forum):_
1) Struggling to get the brake piston moved back in - previously I have used a G clamp to compress the pistons back in , however both rear behaving the same - get so far and then they jam - After checking the forum I am now of the opinion that the rear calipers work differently to front and need the rewind tool which applies pressure while rotating the piston - so maybe this is a non issue - comments ?
2) ABS sensor fault logged as intermittent signal from rear right sensor - so got a few questions :-

a) The rear right wheel appeared to be jammed due to brake application ( even with handbrake off the wheel hard to rotate ) - after getting the caliper off - no issues with wheel bearing turning - could a sticky caliper cause an ABS sensor fault ? NB need to use rewind tool to confirm if the caliper is bad or not.
b) Assuming it is the actual ABS sensor then from what I have read it a pure nightmare to get removed even when the holding bolt is removed - I am stuck at this point - should be a 5mm hex driver , but attempts so far appear to have caused the hex recess to become a circle - any help on how to go from here appreciated to at least let me get the bolt removed. Assuming I get this far then it looks like to remove it will require a lot of chiselling to break up and remove all traces of old sensor before new one fitted.
c) I had read that by attaching a multimeter to the sensor - an AC voltage (~10mV) would be generated when the wheel turned - however on checking both rear sensors today - not seeing any AC voltage generated - any other ways to verify whether a sensor is actually good or bad - hoping that issue solely related to a bad brake caliper to avoid all the pain of replacing the sensor if not the cause of the fault

Attaching output from VCDS relating to the rear sensor
Address 03: ABS Brakes (J104) Labels: 1K0-907-379-60EC1F.clb
Part No SW: 1K0 907 379 AJ HW: 1K0 907 379 AJ
Component: ESP MK60EC1 H30 0107
Revision: 00H30001
Coding: 13422012092200FAC80C04EB901E0091380800
Shop #: WSC 06314 000 00000
VCID: 7AFC29AAF5441991A7-802E


1 Fault Found:
00287 - ABS Wheel Speed Sensor; Rear Right (G44)
003 - Mechanical Failure - Intermittent
Freeze Frame:
Fault Status: 00100011
Fault Priority: 1
Fault Frequency: 40
Reset counter: 44
Mileage: 177305 km
Time Indication: 0
Date: 2019.11.27
Time: 17:28:05


Freeze Frame:
Count: 1
Count: 0
Count: 4608
Count: 83
Count: 53018
Count: 1
Count: 65027
Count: 0

By mechanical failure - any chance this could also be related to the ABS ring rather than the actual sensor ?

Bought the rewind tool and now confirmed that calipers not jammed - so chickening out and going to replace the pads & discs and then see if the ABS fault still shows ( hopefully the rear right wheel piston which was end of its travel is the real cause of the ABS fault - otherwise need to figure out how to get the sensor/bolt out ( and again hopefully issue is not related to the ABS ring on the wheel bearing :(

That is more than likely a rusty wheel bearing pulse ring, I have just done one on a Yeti (same car under the skin) which was 4WD so makes it a bit of a sketch but the 2WD is easy.

Thanks for the info - so is it just a question of cleaning up the ring to get rid of the rust buildup or need to remove bearing to replace the ABS ring ?

It can be rust debris or rust damage to the pulse ring, the black ring on the back of the bearing. I took one off a Yeti today thinking it was the ring but it turned out the new Hella sensor was faulty.

https://i222.photobucket.com/albums/...ps673258be.jpg

Replaced new discs & pads , however still getting an ABS issue logged - so now more looking like it is definately the bearing/sensor which is the issue - so bearing coming off tomorrow.

Best laid plans - ran the VCDS tool and noted that there is no input coming from the sensor - managed to get the sensor bolt removed, however sensor still pretty secured. Went to remove the bearing, thinking I had the correct tool for the job, however my Halfords 12 point M16 spline socket seemed to be getting chewed up trying to break the bolt - after more checking I now think I need a stubby M16 spline XZN socket rather than the one I have - maybe less chance for it to slip out the bolt . New tool ordered and hopefully this will be the last tool I need to buy trying to fix this issue.

I had thought these spline bits were the same whether called M or ZXN, but do remember there is a lot of digging out gunk and rust from the bolt head before it fits

I think they are except the Halfords one has a longer drive end versus the stubby ones - I am hoping that the stubby version of the XZN will be a snugger fit when trying to break the torque - kit I am buying specifically mentions its use for VW/Audi cars ( ~£20) - so we will see :)