i have a 2001 subaru outback.

 

i notice that after 3 or 4 days of sitting idle, the ABS light goes on for the first few miles and then turns off.

 

anyone else experience this problem?

Rust?

Hmm, could just be that the ABS start-up sequence and test takes longer, and the light shines during it. Not sure, you need to have a look behind the wheels, there might be something blocking the sensors.

Could be animals, like rats, mice, birds...building stuff inside your wheels??

A weak alternator that lets the battery run down just enough after four days to cause the ABS circuit to notice it as an error? After a few miles, the voltage comes up enough to turn the light off?

 

Easy enough test with a voltmeter. Also, if idling the car for a few minutes turns off the light, then it probably is unrelated to wheel temperature or objects blocking the ABS sensor.

 

Regards,

Adnan