2.2.51. SPN 1381, FMI 18, Fuel supply pump inlet pressure sensor: Pressure below normal.ΒΆ

Description

The measured fuel supply pump pressure is too low.

Possible causes are:

  • The pre-filter dust load capacity is exceeded. Depending on the fuel quality, this can be considered to be the most common cause, if the filter life is above 100 h.
  • The pre-filter is blocked (significant and sudden dust load from the tank).
  • A restriction/blockage in the fuel line from the tank to the pump. This can be suspected, if some parts of the fuel line have been opened/serviced/changed recently.
  • The vehicle filter is blocked.

Sensor fault:

  • The fuel supply pump pressure sensor wiring is defective.
  • The fuel supply pump pressure sensor power supply is not correct.
  • The fuel supply pump pressure sensor is defective.

Reaction in EEM

The FC is stored and the warning lamp is activated. Engine power is reduced (Degradation Level 1). The CAN message indicates an active fault. The engine functions dependent on the fuel supply pump pressure are not active.

Solution

First save the error log and then obey the solutions that follow:

  • Change both/all the fuel filter elements (and the tank vent filter) according to the fuel filter service instructions.
  • If the filter service does not remove the issue, the restriction/too low pressure is caused by the fuel line.

NOTE: If the error code occurs in cold climate/weather, make sure the tank is filled with winter grade diesel fuel!

  • Examine the fuel supply pump pressure sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Make sure the sensor 5 V power supply is correct.
  • Try the operation with another fuel supply pump pressure sensor to see if the fuel supply pump pressure sensor is defective.

See Fuel supply pump inlet pressure sensor for reference.