This engine P1251 Code is a common code and it is meaningful. If the correct meaning of the code is not located, you cannot solve the car engine problem. The problem of the car engine is powertrain what can be solved using hand tool. If you are not an expert automobile engineer or you have no all tools, you should not try to solve the car engine. Take the car to automobile repairing center where you will get skilled automobile engineer to solve the problem from the car engine. Fix the car engine properly and when the car engine is fixed, a test drive is suggested.