brunnj

My sister's 03 Sentra with the 1.8L engine is pulling a P0462 code, fuel level sensor A circuit input low. We replaced her fuel pump for some difficulty starting the car and the code has come back.
We checked the resistance on the fuel level sending unit and it is correct according to the Haynes manual. My question is, what is the brown sensor that sits just below the level sending unit on the outside of the pump housing? I have included a picture with this post. The sensor is brown and bullet shaped, with a blue and black wire soldered onto spade terminals on the flat end of the sensor. Can anyone help here? Thanks.