You need to know the real meaning of the car engine code and you have to have all tools for solving the car engine problem. The car engine P2509 Code is related with the car engine and meaning of the car engine code should be taken from the right source. The right source is automobile manufacturer of your car. Do not allow wrong meaning or general meaning of the code first. You should verify the problem and it is possible if you know the right meaning only. Once the car engine is ok, you must choose it for a test drive.