My check engine light is on, the car ran out of battery and after jumping it, it is running kind of poorly, idling rough, etc. I plugged in the OBD-II scanner/reader, and it "has power" (green backlight works), but nothing comes up, it just reads...emptiness. Honda Accord 97. Thoughts?
Turns out this particular issue wasn't due to me running the car out of battery (I believe) but actually to a blown fuse. I guess I had previously left the OBD II plugged in for awhile and apparently if anything else "on that circuit" is turned on it can blow the fuse, and my kids may have turned something on and voila, fuse blown. Another effect of having left it plugged in was the keys were also in so it ran down my battery, unrelated.
In this case it was a 7.5A fuse in the "internal" fuse compartment (not the one under the hood) typically its one that deals with dash stuff/cig lighter or what not. Replacing the blown fuse and check engine went off, car runs OK again (phew).