The general meaning of the engine P0721 Code is called automobile dictionary meaning and it is p for Powertrain Code Problem is related engine, transmission and emissions systems. 0 for SAE – Generic. 7 for Auxiliary Emission Controls. 2 for Air Conditioning (A/C) Clutch Feedback Circuit High Voltage and 1 for TFP Valve Position Switch-Drive Without Drive Ratio. Do not allow any wrong meaning of the code for solving the car engine. This automobile dictionary meaning of the code is not right meaning what you can use at primary basis for solving the car engine. The automobile engineers knows well when the general meaning of the code can be used.