The Transmission Fluid Pressure Sensor (TFP) is located on the side of the valve body inside the transmission. It may also be screwed into one side of the transmission body. The function of this sensor is to convert the pressure from the mechanical transmission into an electrical signal that is sent to the Transmission Control Module (TCM) or Powertrain Control Module (PCM). This signal is used to determine the transmission operating pressure or also to determine when a change occurs.
If the TFP Sensor input “A” does not match the normal operating voltage stored in the TCM / PCM memory, the error code P0841 OBD2 will be set.