The meaning of the car engine P3406 Code lets you know the problem of the car engine. Do not solve the car engine by any untrusted person. For solving the problem, you must depend on the automobile manufacturer or an automobile technician. The automobile dictionary meaning of the code is general meaning and it 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 6 for Cruise Control System – Vehicle Accel Too High. When the car engine is ready, you must test the car by a test drive.