abs warning light

[Laur]

Hi first time posting.
My lad has been given a 2002 polo 1.4 75bhp by his aunt only 26k on it.she has had it from new always main dealer serviced but has a problem that keeps reoccurring the abs light will come on stay on for a while the go out it may not happen for weeks the deale replaced the abs unit couple of years ago any ideas

[Mr Miyagi]

Is the ABS kicking in on brakeing all the time when the light is on?

[Laur]

no brakes normally abs still seems to work I've taken it out and brake hard enough to get it working