The car engine problem is serious problem what may cause of the serious accident. Fixing the car engine is important and find the real meaning of the car engine code. By the real meaning of the code, you can know more about the car engine problem and solve the engine problem properly. The automobile dictionary meaning of the car engine P0921 Code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 0 for SAE – Generic. 9 for Fuel And Air Metering (Injector Circuit Malfunctions Only). 2 for Air Conditioning (A/C) Clutch Feedback Circuit High Voltage and 1 for TFP Valve Position Switch-Drive Without Drive Ratio.