Okay I see what you are doing.

If I have no DTC Codes mine will still clear them. It says Erase successful when I try to clear them. The end result is that it will clear the readiness monitors and they will flash at the top of my scanner indicating that the codes were recently erased.

Your scanner needs to show the status of the readiness monitors. If they are not set, then the codes have recently been cleared. If they are all ready, and there are no codes it is PROBABLY OK. I have had codes that I could clear and they wouldn't show up for several days or weeks after the readiness monitors were set to OK.

Also my scanner will check for OEM specific codes. It isn't great at that but often I can pull codes that the Manufacturer will generate but not trip and OBDII code. Mine is just a $100 to $200 Craftsman which is a re-badged Acctron.

Make sure your scanner will display the Rediness Monitors and you should get what you want. Mine are at the top of the screen and display as colored circles with abbreviations like O2 or CAT in them. They change color/flash to indicate not set, set or malfunction.

It's also nice to have them be able to scan while driving. I plug it in and drive, it automatically scans every minute while driving. I drive until it resets the monitors or trips a code. Beats having to drive 50 miles and hope the car is ready for emissions / inspection, Maye they all do that