The automobile dictionary meaning of the code P0603 is important thing and you need use the right meaning of the code for sixing the car engine but if you use automobile dictionary meaning of the code, it is not right way of fixing the car engine. The automobile dictionary meaning of the code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 0 for SAE – Generic. 6 for Vehicle Speed Control And Idle Control System. 0 for IC Circuit High Voltage and 3 for Transmission Control Module Reprogrammable Memory. The powertrain of the car engine should be fixed for solving this code problem.