The car engine P2778 code seems a kind of powertrain problem and it is easy to fix the car engine problem. Diffusion of cylinders is realized by releasing a synchronizer pin that generally meshes the cam follower and rocker arms. The car engine P2778 code solves the synchronizer pin is unconfined by using hydraulic burden which is measured by a dedicated solenoid. The general meaning of the code is p for Powertrain Code Problem is related engine, transmission and emissions systems. 2 for MFG – Manufacturer Specific. 7 for Auxiliary Emission Controls. 7 for Vehicle Speed Output Circuit and 8 for PCM Stack Overrun.