No reading from the OBD-2 on 2004 Ford Taurus

The OBD-2 has detected a malfunction, but the scan tool can't get a reading. What may cause this?

Asked by for the 2004 Ford Taurus
I assume your light is on.
if there is no power to the scan tool, there is a fuse that provides power to the obdII connector. it is usually the cigar lighter fuse.
if it does have power and cannot communicate then there is a module that is pulling the system to ground and must be diaged by a shop.

Thanks Roy. As you said the fuse to the cigar lighter was out and after replacing it, I was able to get a reading.