Massey Ferguson E4374.08 – Engine ECU / e3 SCR emissions control module: DEF Pump Speed Issue

The control module has detected that the Diesel Exhaust Fluid (DEF) pump motor is not operating at the commanded speed. This prevents the system from building or maintaining the correct pressure required to inject DEF into the exhaust stream, which directly impacts the Selective Catalytic Reduction (SCR) system's ability to reduce emissions.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624

1. 1

   Check for related electrical codes (e.g., E4375.3, E4375.4, E4375.5) which indicate a wiring harness issue rather than a pump motor failure

2. 2

   Inspect the electrical harness and pins at the DEF pump for corrosion, moisture, or loose connections

3. 3

   Inspect DEF fluid quality in the tank for contamination (dirt, diesel, or water) or heavy crystallization that could bind the pump motor

4. 4

   Check heated DEF lines and the tank breather/filters for blockages that could cause the pump to deadhead or cavitate

1. 1

   Preparation

   Safely park the tractor, turn off the engine, and disconnect the battery. Thoroughly clean the area around the DEF pump to prevent dirt from entering the SCR system.

2. 2

   Disconnect Electricals

   Unplug the electrical harness connector from the DEF pump dosing unit.

3. 3

   Disconnect Fluid Lines

   Carefully disconnect the DEF supply and return lines. Note: Have a clean catch pan ready for spilled fluid, and immediately cap the lines to prevent contamination or crystallization.

4. 4

   Remove the Pump

   Unbolt the mounting hardware securing the DEF pump to the chassis/bracket and remove the faulty unit.

5. 5

   Install the New Pump

   Mount the new AdBlue Injection Dosing Unit and tighten the bolts to OEM torque specs.

6. 6

   Reconnect

   Remove the caps and reconnect the DEF fluid lines (ensure O-rings are seated properly). Reconnect the electrical harness.

7. 7

   Clear Codes and Test

   Reconnect the battery. Use a diagnostic scan tool to clear the E4374.08 fault code. Run an SCR system test or forced regeneration to prime the pump and verify it operates at the correct speed and pressure without leaking.