Nunga

Hello everyone. I have a 2006 inpreza with the check engine light that is on. Ive tryed to read it with a Bluetooth obd2 reader but no matter what app i get for my phone it cant seem to get any data off to get a code. All i can seem to do is clear the code but the light just comes back on as soon as the car is started. I saw on a thread there is a black plug you can connect under the dash to manually pull the codes but i cant seem to find that. There is only a green plug there and that doesn't work when i plug that in. So im asking for help in reading the code so i can fix it. Cheers.