This engine P1620 Code is meaningful and according to the automobile dictionary 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. 2 for Air Conditioning (A/C) Clutch Feedback Circuit High Voltage and 0 for Transmission Engaged At High Throttle Angle. The engine system, in conjunction with the engine control module or powertrain control module and starts the engine P1620 code solenoid controller to control oil compression to the engine mechanism that is connected in the valve method to switch valve timing between High and Low.