It should perform a self test when you turn the ignition on every time, when I used to practise my fwd power slides with the aid of the handbrake it used to bring the abs light on.

Turning the engine off and back on again cleared it straight away though.

Is the sensor gapped properly?

Try running it about for a while, I know that if the car's engine management light comes on for a brief glitch in the system, it will stay on for the next 20 times the car is started until it will go out again.