The code P0040 Code is related with the car engine and it is necessary to fix the car engine. For getting the real meaning, read the manufacturer meaning. Do not use general meaning what you will get from online. The automobile dictionary meaning is not appropriate thing for the car engine problem. The general meaning of the code is available and it is free. The P0040 engine code is a kind of powertrain problem and it is easy to fix. According to the manufacturer and model number of the car, the meaning of the code changes. Do not drive the car with any type of car engine problem.