The engine P1633 engine code is a kind of powertrain problem and it is a small problem. You should not fix the car by the wrong meaning of the code. The engine code’s meaning is p for Powertrain Code Problem is related engine, transmission and emissions systems. 1 for MFG – Manufacturer Specific. 6 for Vehicle Speed Control And Idle Control System. 3 for Cruise Control Servo Indicates Low. 3 for Transmission Control Module Reprogrammable Memory of the car engine code P1633. Although fuel economy was enlarged, the acceleration was extremely cooperated, and the damage of engine vacuum led to a unsafe loss of braking support when the engine P1633 code system was in 4 cylinder mode.