4.2.235. SPN 520244, FMI 31, Rail PRV is forced to open; perform pressure shockΒΆ

Description

EEM4 monitoring system has forced PRV to open by increasing rail pressure. This is engine safety function.

Possible causes are:

  • The rail pressure sensor is defective
  • The fuel rail is defective
  • The high pressure pump is defective
  • The PRV is defective
  • The injectors are defective
  • The control unit 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.

Note: fault code: Rail PRV recognised as open, SPN 520208 FMI 31 is also active due the forced opening.

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 injector solenoid valve wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Check the rail pressure sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Check the operation with another rail pressure sensor to see if the sensor is defective.
  • Check the pressure relief valve visually for impurities. If there are impurities, clean the valve or replace it with a new one. Tighten the valve according to the instructions in the service manual.
  • Check the fuel lines visually to detect mechanical failures.
  • Check the ECU operation with another EEM4 controller. If the system is functional and the fault is not active with the replacement ECU, then the original ECU is defective