The TFP Sensor (Transmission Fluid Pressure) is located on the side of the valve body, internally in the transmission. Its function is to turn transmission pressures into an electrical signl, which is transmitted to the PCM (Powertrain Control Module) or TCM (Transmission Control Module). The voltage signal provided by the TFP sensor is used by the PCM / TCM to calculate the pressure required for efficient transmission operation.
The setting of DTC code P0845 OBD2 indicates that the PCM or TCM detected that the TFP Sensor “B” circuit input is outside acceptable parameters with respect to the normal operating voltages, which are determined by the manufacturer.