Collect the real meaning of this car engine code what you have found from the car engine after the car engine is tested. This car engine P3408 Code is found from the car engine and you should use the real meaning of the code for solving the car engine. If the real meaning of the code is not found, you may use general meaning for solving the car engine. The general meaning of the code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 3 for SAE – Generic. 4 for Transmission. 0 for IC Circuit High Voltage and 8 for PCM Stack Overrun.