Interesting info. I do usually have reader plugged in, due to o2 sensor codes popping up and i haven't had chance to replace sensors or cat. I will remove it and see.Do you have any kind of obd2 reader plugged in all the time? I noticed that with my ultra gauge plugged in, the DTE stays pegged up at 400+ all the time.
I'm not too worried as I use the ultra gauge to get the same feature and many more.
And... I've never seen 400 miles on a tank