When you need to fix the car engine, you should allow an automobile engineer to fix the car engine problem. The car engine P3456 Code is found when the car engine was tested. If you do not use the right meaning of the code, it becomes difficult to solve the car engine. The automobile dictionary meaning of the code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 3 for SAE – Generic. 4 for Transmission. 5 for TP Sensor Learn Not Complete and 6 for Cruise Control System – Vehicle Accel Too High. Solve the car engine properly by an expert engineer’s help.