service engine on - but no codes?

[Ashaman074]

Hi,

My wife drove my 2005 4.4l X5 yesterday and came back telling me the "Service Engine Soon" light was on. I went out to the garage and hooked up my OBDII code reader (a mid-range Actron) and it reported there were no codes. It is communicating with the vehicle, it reads, but it reports there are no codes. I then performed the emissions readiness test, it passed no problem, in fact it reports the "MIL" status to be off. Real-time data also reports that the warning is "off."

I then had it scanned with INPA; it found some errors, but they appeared to be random/minor issues (seat adjustment, mirror adjustment, etc). I went ahead and used it to "clear error memory" and re-ran the test; it came back with no errors found. However, the "Service Engine Soon" light is STILL illuminated.

I did fill the car up with gas right after work, so I checked the gas cap, it was on properly though. A bit of a coincidence that it should come on right afterwards I suppose, but if there were an issue wouldn't an error code be logged anyway?

In short, I am a bit puzzled how the light can be on, yet I haven't found any codes yet.

Anyone have any suggestions?

TIA!