xsara picasso abs non function

[krl696]

hi, abs light on and showing non function been to local garage for a diagnostic check and says"no communication with ecu"they think ecu faulty
(brakes work fine but abs doesn't seem to come in when I try emergency stop... wheels skidded)
just wondering if its been encountered before if so what are causes
the vehicle is a 2005 1.6 8v petrol
many thanks in advance

[MikeT]

AFAIK, causes can be broken wire/connector, damaged, obstructed or misaligned reluctor ring or sensor (all of which you have x4) or as your local garage opined, the rather expensive ECU, it's wiring and fuse(s).