Cheers Del  I tried a reader, mine didn't clear the light. I cleaned the sensors too.  In the end I took it to a Bosch garage, they found a nsr sensor not working, replaced (£90 from Stratstone) total job £211. all ok now, it could have been worse.   If stratstone had told me it was the sensor I would have bought and fitted one. so  much for main dealer loyalty.   E bay price about £70 ish for a second hand one!!!