Sensors don't get reset. They just do their thing and report things to the computer. The problem is no two sensors are ever exactly alike. The computer learns the characteristics of each one by comparing their readings and engine operating conditions to each other. When you disconnect the battery, that will erase most fault codes, but it erases all the other stuff in all the other computers' memories. Your car is new enough to have at least two dozen computers, and most of them have memories that will get erased.
Your Engine Computer also learns "short-term fuel trims", (STFT), and "long-term fuel trims", (LTFT) as you drive. Those "look-up tables" will all have to be rebuilt the next time you drive the car after the battery was disconnected. You likely won't even know that is taking place, but until that is completed, fuel mileage, emissions, and engine performance won't be at its best.
Most importantly, too many people obsess over doing whatever it takes to get the Check Engine light to go off. You have an unusual case where we know what caused a problem to be detected, but under normal conditions, when the Check Engine light turns on, the last thing you want to do is disconnect the battery or let it run dead. The computer set the fault code to provide really valuable information, and you don't want to lose that until the codes have been read and recorded.
Think of that fault code as going to the doctor with a pain, and you can tell him where it hurts. Erasing fault codes, then trying to figure out where to start troubleshooting is like taking your dog to the vet. He can't explain where it hurts.
Tuesday, March 31st, 2015 AT 2:58 AM