3.2.394. SPN 522072, FMI 31, Rail over pressure monitoring time exceededΒΆ

Description

The EEM monitoring system has detected that the rail over pressure monitoring count has been exceed. In the fault condition when e.g. the rail pressure sensor is defective, there is a possibility that the rail pressure might rise too high. The rail over pressure timer is always running in the fault condition. When the timer is full, this error is released.

Reaction in EEM

The FC is stored and the warning lamp is activated. The CAN message indicates active fault. The engine start is disabled.

NOTE: Rail over pressure monitoring time exceeded counter needs to be cleared with the WinEEM4 service tool.

Solution

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 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 with the Service Tool test function, or have the pump inspected by an authorized Bosch service dealer.
  • 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 sensor is defective.
  • Check the pressure control valve: Look for possible valve stucks and inspect them accordingly (e.g. faults with the wiring and the connectors).
  • Check the electric presupply pump: Look for possible relief valve stucks and inspect them accordingly (e.g. faults with the wiring and the connectors).
  • In case of a damaged pressure control valve (PCV), high pressure pump or a wiring harness, replace the damaged parts according to the instructions in the service manual.

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

See Rail pressure sensor for reference.