Ok all..
I had this message coming up more and more, ending up having to stop and start 4 times to get home in the space of 2 miles..ARGH...
So, as advised I jacked up the rear cleaned the ABS sensors.., yes they were filthy..

Then did the same with the fronts, however I could not actually remove them, without damage I suspect, ..Hmmm..so I cleaned the cogs, brushed in between the cogs and sensor, with copious amounts of WD40 Contact Cleaner..Brilliant stuff for my normal activities.
Started engine..down the road..ASC Trac again.....double Hmm..
So next I unplugged the the ABS unit and then removed electronics from the pipework and pipe manifold..all with a lot of juggling and squeezing.. I then cut open the corner of the abs box, resoldered the 2 wires, even though they looked ok.. put it all back, bled the brakes round from back to front..Ok I thought..

Tried again, down the road, limp mode yet again and egine light on...., Ho bl**dy hum..

So after more reading, I ordered a new throttle position sensor.. this will be easy I thought..
I could not get the screws undone..Hmm..
I ordered new set of torqx.. A doddle I assumed.. torqx still not fittiing & still don't have the right size.... after more digging deep, I found out that the torqx are 5 point???
Why oh Why..Whats wrong with 6, Yes 5 maybe stronger, but on a M4 bolt neither here nor there!!
Anyway Amazon and £4.99 later the next dry day , it unscrewed..Hurrah!!!,
I disconnected the battery then turned ignition on, and shorted the ground to positive, to discharge everything again(did that befere removing the ABS unit of course!!!)..
This car has had more resets than my windows PC!!
I carefully marked the setting position and installed new sensor (ebay, but not the cheapest, around but £40) It actually, looked identical to the Denso original..but with the OEM number on it..
Set it up and, reconnected, turned on ignition, held throttle down for 5 seconds etc. started the engine..wow did it rev....So ah..
Anyway I loosened the sensor enougn to rotate it and started again..eventually finding the correct position for about 650 RPM?
Anyway, guess what?
The engine light went out , and it seems all is well again once more..Hurrah..

So a learning job..Maybe check throttle sensor first, who knows..But at 125k miles I can forgive this..

I have not yet invested in an OB2 reader,....any good suggestions out there please?

Now for lower Shocker mountings and or shockers.. to stop my 50mph + jitter...

I hope this short tale makes someones life a little easier, in the future!

..

 

Writing up a major pain in the butt with humor but explaining a DIY that will help others, a big plus and thanks.
A OBD II with blue tooth is a very reasonable price and give a reading while driving on things like oil pressure and water temperature.
Wish I could tell you which one but as yet to get my own. Still use my old OBD.

 

Why were you unable to remove the two front wheel speed sensors? They are held in place by just one bolt each. If those bolts have rusted, spray several applications of PB Blaster on them, let it soak for a day or more, and then carefully remove the bolts and then the sensors. Vigorously scrub those sensors with an old toothbrush using a mixture of dish soap and water. Let them air-dry before reinstalling them. I have been doing this to all four wheel speed sensors on my wife's 2006 XK8 at every oil & filter change / tire rotation for more than a decade now. I have not seen any ABS or Traction warning icons on the dash since I began my routine sensor-scrubbing intervals way back then....

Be sure to check the condition of the sensor wiring harnesses when you have the wheels off the car. Their rubber boots at the sensor electrical plugs tend to split and crack as the years go by, allowing rainwater to ingress into the wiring harnesses. If you notice any cracking, you can carefully wipe down the boots and then cover them with a generous blob of neutral-cure RTV silicone. Allow the fresh RTV to cure for a few hours before plugging the wiring harnesses back into the sensors and reinstalling your wheels. I did this the very first time I removed the sensors to scrub them, and my original RTV application remains solidly in place to this day....

 

Ah ok.. about OB2

I hope this will be helpful!

 

Ah I was running on limited time and needed to check it all rapidly. Also the rears came out easily, and the front bolts came out but the sensors would not budge, I did not wish to apply too much force! . I will get to them one day..
Next spring, I think either shockers or new lower bushes!