The general meaning of the P040D Code is not necessary to solve the car engine. The engine code P040D OBD2 rumors a sensor liability, extra of the sensor is doubtful to tenacity the original problem. The fault is the most likely to be triggered by the schemes that the sensor is monitoring, but might even be triggered by the cabling to the sensor itself. Do not follow the general meaning of the code and the general meaning of the code may create more problems. You should follow the right meaning and you have to get the real meaning what is related with the manufacture and model number.