I had the same fault last year, I have access to a Bosch kts on a laptop so I don't know if you can do the same with TOAF , I measured the speed of the wheel sensors on a quiet lane with it on my knees and at 5 mph three wheels read 5 mph except my n/s/r which read 5 then 0 the 5 then 0 etc. I fitted a new hub and within a few yards the light went out and stayed out. Still good to this day.