Hello Dina,
the error code 5057 on a FB-12 means that the pump motor speed sensor is defective.
1. Confirm that the connectors and terminals of pump motor
speed sensor are not disconnected and not loosened.
2. Measure the resistance of harness between the cargo handling
controller and the pump motor speed sensor.
Judging: Between CN1-P terminal No.27 (white) and
pump motor speed sensor terminal No.1 (white)
Between CN1-P terminal No.28 (black) and
pump motor speed sensor terminal No.2 (black)
3. Check the pump motor speed sensor. Repair or
replace it.
4. Check the gear of motor pump (poor mesh of gear
with the sensor, entry of magnetic substance).
Repair or replace the motor.
5. If normal in the above check, replace the cargo
handling controller.
Kind regards
Marc