This engine P0977 Code is meaningful and it tells you about the car engine problem and location of the problem. You need to take step for the solution of the car engine. The engine system, in conjunction with the engine control module (ECM) or powertrain control module (PCM), starts the P0977 code solenoid valve to control oil heaviness to the engine mechanism that is connected in the valve system to switch valve timing between Low and High. If the engine solenoid regulator has an open or short circuit, a DTC is stored. Do not apply false meaning for solving the car engine problem.