The automobile meaning of the car engine P1868 Code is p for Powertrain Code Problem is associated engine, transmission and emissions systems. 1 for MFG – Manufacturer Specific. 8 for Ignition System Or Misfire. 6 for Control Module Throttle Actuator Position Performance and 8 for PCM Stack Overrun. The engine method in conjunction with the engine control module or powertrain control module, triggers the engine P1868 code solenoid valve to regulator oil heaviness to the engine mechanism that is installed in the valve system to switch valve timing between High and Low. If the engine solenoid valve has a short circuit or open, a DTC is deposited.