If you have a better quality OBDII code reader you can even look at some of the engine data such as throttle angle and such,mine I use is an ACTRON Is one of the better ones they sell model 9175 or something like that.......I use it to clear codes and I can use it on some Trucks with the K21/25 engine to look at engine parameters while it's running,not all trucks will do this but have found some that will