Massey Ferguson 3361.31 – Engine ECU: DEF Injector Has Not Opened Or Closed As Expected

The Engine Control Unit (ECU) has detected an improper mechanical or electrical response from the DEF injector (dosing module), indicating it has failed to open or close as commanded. This malfunction disrupts the precise metering of Diesel Exhaust Fluid (DEF) into the exhaust stream, which is essential for the Selective Catalytic Reduction (SCR) system to properly reduce NOx emissions. If left unresolved, this issue will lead to increased emissions and eventual engine power reduction.

• 4710
• 7724S
• 5712SL
• 7722S
• 7722
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 4708
• 7726S
• 4707
• 4709
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 5710 SL
• 5711 SL
• 5712 SL
• 5713 SL
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714 S
• 7715 S
• 7716 S
• 7718 S
• 7719 S
• 7720 S
• 7722 S
• 7724 S
• 7726 S
• 8650
• 8660
• 8670
• 8680
• 8690

1. 1

   Inspect the injector tip and nozzle for DEF crystallization buildup that could be blocking the spray

2. 2

   Check DEF fluid quality to ensure it is not contaminated with dirt, debris, or non-ISO-compliant fluid

3. 3

   Inspect the DEF lines between the DEF pump and the injector for blockages, kinks, or leaks that would prevent pressure from reaching the injector

4. 4

   Verify the electrical connections and wiring harness to the DEF dosing module are secure and free of corrosion or damage

1. 1

   Clean or Flush

   If crystallization is found on the injector tip, clean it carefully. If the DEF fluid is contaminated, drain the tank, flush the system, and replace the DEF filters.

2. 2

   Replace the Injector

   If the injector is mechanically stuck closed, internally damaged, or fails to open after cleaning, replace the DEF Dosing Module/Injector.

3. 3

   System Calibration

   After replacing the dosing unit, use a diagnostic tool to clear the fault codes and run a forced DEF dosing test or system calibration. This verifies that the ECU can now detect the proper pressure drop when the injector is commanded open.