I'm guessing this is the ABS sensor, how do i find out which one?
anyway to reset it and see if it comes back?

 

Drive to AutoZone. Have them read the code. Find out what the code means.

Better yet, buy a VAGCOM and do your own diagnostics whenever something comes up.

I could be many different things. Wheel speed sensor, lateral accelerometer, longitudinal accelerometer, tone ring, hydraulic system self diagnostics, broken wire, yaw sensor, steering position sensor. Pick one or more!

 

had one on my 01 jetta vag-com tells you which one, works on all vw audi products free on-line updates, and a service manual good investments, oh its a 30 minute job to replace a wheel sensor, $50 on my jetta for the part

 

I agree to him. It is better to have a diagnostic check before replacing the sensor. There many possible reasons as mentioned. You might end up in expensive repair without checking what went wrong.

 

And between the diagnostic test, and replacing the sensor, try blowing the crud off it.

Sensor that reads the tone ring is magnetic, and metallic brake/road debris can stick to it and cloud the reading. Been there...