The engine code P1817 DTC is exactly mentions to the camshaft timing. In this case, if the cam timing is over-retarded, the engine light will be illumined and the engine code will be set. You need to get the meaning of the car engine code for identify the real cause of the car engine problem and you must look for the right meaning what is found from the car manufacturer. You can use the automobile dictionary meaning of the code for solving the car engine but you must give the priority to general meaning of the code. Do not fix the car engine in wrong way.