There are several causes found of the problem of the car engine P1644 Code. You should know the exact meaning of the code and find the real cause of the car engine problem. It is possible to identify the real problem of the car engine if the car is hand over to an expert automobile engineer. The automobile engineer can use this expertise and machines to know the exact cause of the car engine problem. However, do not drive the car with the car engine problem, you may face different new problems in the car engine what can be more serious for your life.