4.2.57. SPN 157, FMI 16, Rail Pressure control: Pressure CRITICAL highΒΆ

Description

The measured rail pressure is above the warning limit.

Possible causes are:

  • The high pressure pump is not working correctly.
  • The rail pressure sensor wiring is defective.
  • The rail pressure sensor power supply is not correct.
  • The rail pressure sensor is defective.

Reaction in EEM

The FC is stored and the warning lamp is activated. Engine power is heavily reduced (Degradation Level 3). The CAN message indicates active fault. The engine functions dependent on the rail pressure are not active.

Solution

  • Check the high pressure pump: Look for possible high pressure pump faults and inspect them accordingly (e.g. faults with the wiring and the connectors)
  • Check the high pressure pump operation, or have the pump inspected by an authorized Bosch service dealer.

To check the electrical defects, check the rail pressure sensor, the sensor wiring and the controller input: First save the error log and then erase it. Restart the ECU after erasing the error log. If the fault occurs again during the next driving cycle, check the following paths:

  • Check the rail pressure sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Check the 5 V power supply to the sensor.
  • Check the operation with another rail pressure sensor to see if the rail pressure sensor is defective.

NOTE: The rail pressure sensor removal, inspection and replacement should be performed only by qualified injection system service personnel. Special instructions may apply.

See Rail pressure sensor sensor for reference.