freeze frame tells you what was happening when it threw the code.i carry my scanner in my suburban because if say i'm cruising along and have to hit the brakes all the sudden it will throw a pp420 code which is a bad catalyst.but that is not my problem.i can drive this thing for 5000 miles and if i don't have to get on the brakes hard it does not throw a code.i bought mine at o'reilly's for like 120 bucks.well worth it.