The engine P0728 Code is very important thing what helps you for solving the car engine problem. Do not use wrong meaning of the code for solving the car engine problem. The automobile dictionary meaning of the code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 0 for SAE – Generic. 7 for Auxiliary Emission Controls and 2 for Air Conditioning (A/C) Clutch Feedback Circuit High Voltage 8 PCM Stack Overrun. The powertrain problem of the car engine is easy to fix and you do not need to fix the car engine by yourself. You should ask the automobile engineer to fix this issue.