2.2.340. SPN 521025, FMI 31, EAT Monitoring: SCR efficiency not OKΒΆ

Description

The SCR efficiency is not valid.

Possible causes are:

  • The SCR system is unable to dose.
  • The DEF dosing module is defective or blocked.
  • The used reducing agent (DEF/AdBlue) is contaminated.
  • The SCR catalyst is defective.

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:

  • Perform catalyst cleanup function with an official service tool.
  • Check the used reducing agent (DEF/AdBlue) quality. If there are any suspicions that a poor quality reducing agent has been used, the tank needs to be emptied, flushed and refilled with valid reducing agent.
  • Check the DEF system operation. Make sure the SCR system is able to dose the DEF/AdBlue.
  • Check the operation with another DEF dosing module to see if the dosing module is defective.
  • Check the SCR catalyst condition. Remove the dosing valve and look inside the catalyst and the nozzle. Check for a possible DEF/AdBlue deposit problem or a blockage.