The charge air cooler temperature sensor (CACT) is used to measure the temperature and concentration of the air passing through the charge air cooler. This data is sent to the PCM (Powertrain Control Module) to be compared with the engine coolant temperature and EGR (Exhaust Gas Recirculation) temperature to check cooler performance. This sensor is usually located in the same housing as the Boost Pressure Sensor.
The DTC P007D OBD2 code setting is due to the PCM detecting excessively high voltage signals in the charge air cooler temperature sensor circuit.