The engine P0621 Code helps to fix the car engine and that is why, you should get the right meaning of the code. You should hand over the car to professional automobile engineer who knows well how to solve the car engine’s problem and right meaning of the engine. If the real cause of the engine’ problem is not identified, it is difficult to solve the car engine’s problem. By the symptoms, you need to fix the real cause of the car engine. Do not drive the car with the car engine’s problem. You should take action to solve the problem immediately.