The engine P1686 Code is meaningful and right meaning of the code helps to fix the car engine fast. The engine P1686 code seems a kind of powertrain problem and this problem is not difficult to solve. The original system turned off the opposite pairs of cylinders, permitting the engine to have 3 diverse configurations and displacements. The engine P1686 code had an elaborate diagnostics process, including showing engine error codes on the air conditioning display. However, the system was troublesome, misinterpreted by customers, and a rash of unreliable letdowns led to the tech being fast discharged. Do not drive the car if the car engine is not fixed.