Alfa 164 ABS Warning

Hi,

I have a 1990 Alfa 164 3.0 V6, and the ABS warning light on the dash comes
on intermittently after a recent WOF check.

Self check is OK when turning ignition on, and after starting the car. Light
comes on while driving after 5-10 minutes. No other warning lights come on.
On the same day of the WOF check I'd also replaced a bulb behind the rev
counter, but all others are OK.

Any ideas, as the WOF shop says take it to my Alfa dealer to diagnose,
and/or reset the ECU. More likely that the dealer will charge $$ and
probably won't even find the fault!

Cheers,
Don.

1996 Fiat Coupe 2.0 16V Turbo
1996 Alfa 145 1.6 Lusso
1990 Alfa 164 3.0 V6