Nissan Sentra B15 2003 board

Good afternoon, I have a B15 Nissan B15 with a problem on the board, the car when it lights in cold lifts all the needles perfectly but after an hour of going on the way the needles come completely down to the temperature.
In the DTC I came out that the speed sensor is in malfunction, but I do not understand why the other needles go down, what could it be? The speed sensor? or what? thank you...