4.2.127. SPN 4332, FMI 0, SCR system ERROR: DEF over pressure detectedΒΆ

Description

The EEM4 monitoring system has detected an SCR system ERROR. The monitored DEF pressure is above the normal operating range.

Possible causes are:

  • The DEF backflow line is blocked.
  • The DEF backflow line connector is blocked.
  • The DEF tank ventilation is defective.
  • The DEF supply module main filter is defective.
  • The used reducing agent (DEF/AdBlue) is contaminated.
  • The DEF supply module is defective.

Reaction in EEM

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

NOTE: The present fault is classified as an emission related fault. Engine power will be reduced after a certain time defined by an authority.

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 DEF line heater operation if system has been defrosted and fault is active.
  • Change the DEF supply module main filter.
  • Change the DEF supply module backflow connector.
  • Remove the DEF backflow line to detect the possible blokage.
  • Check the used reducing agent for contamination and change it if necessary.
  • Check the operation with another DEF supply module to see if the supply module is defective.