2.2.193. SPN 4334, FMI 1, SCR system: DEF dosing pressure below normalΒΆ

Description

The EEM monitoring system has detected an SCR system ERROR. The pressure during the metering control is too low in the DEF supply module.

Possible causes are:

  • A possible leakage in the DEF hoses, the connectors or the supply module. (A DEF leakage on the system pressure side or an air leakage on the suction side.)
  • The DEF supply module main filter is defective.
  • The DEF tank ventilation is blocked.
  • The DEF supply module inlet filter is blocked.
  • The filter in the DEF tank sensor is blocked.
  • The used reducing agent (DEF/AdBlue) is contaminated.

Reaction in EEM

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

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

Solution

First save the error log and then do the procedure that follows:

  • Check the DEF system visually to make sure there is no leakage in the DEF connectors, the hoses or the supply module.
  • Change the supply module inlet connector.
  • Change the DEF supply module main filter.
  • Change the DEF tank suction filter.
  • Verify that the tank ventilation is working properly.
  • Examine the used reducing agent for contamination and change it if necessary.
  • Change the DEF supply module backflow connector.