I just fixed the ABS light on my recently acquired Clio.
I checked the wheel side first.
You can possibly see enough with the wheels still on, and turned to one side, however i removed the wheels to make life easier.
If you look inside the wheel hub, at the end of the drive shaft is the "reluctor", which is a toothed wheel. This is "read" by the plastic ABS sensor.
First side i checked was very rusty, but teeth appeared all there. Second side the ring had come off completely.
I found new ABS rings on
for about £4 each. Hopefully if you have one still on the car you can count the teeth. Don't know about the Scenic, but for the Clio they list them with 26 or 44 teeth.
You need to pop the end of the driveshaft back through the hub to get the new reluctors on the end of the driveshaft.
It's worth mentioning perhaps, that the ABS light didn't go out straight away, but by the time i reached the end of the road (100m or so) the system had clearly reset itself.