2.2.192. SPN 4334, FMI 0, SCR system: DEF dosing pressure above normalΒΆ

Description

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

Possible causes are:

  • The DEF backflow line is defective. (A possible blockage or a mechanical defect.)
  • The DEF supply module backflow connector 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:

  • Examine the backflow line visually to detect any mechanical failure eg. if the hose is flattened.
  • Remove the backflow line from the DEF tank. Perform the dosing test with the service tool. There should be an ongoing flow from the hose. Check also the backflow connection from the DEF tank.
  • Change the DEF supply module backflow connector.
  • Check the used reducing agent for contamination and change it if necessary.