Massey Ferguson 004374.14 – ACM: DEF Pump Speed Issue (ECU)

The After-Treatment Control Module (ACM) has detected that the Diesel Exhaust Fluid (DEF) pump is running at a speed that is higher than expected for the current pressure in the system. This suggests the pump is working harder than it should to generate the required DEF pressure.

• 4607 M
• 4609 M
• 4610 M
• 4708
• 4709
• 4710
• 5709SL
• 5710SL
• 5711SL
• 5712SL
• 5713SL
• 5709 S
• 5710 S
• 5711 S
• 5712 S
• 5713 S
• 6612
• 6613
• 6614
• 6712 S
• 6713 S
• 6714 S
• 6715 S
• 6716 S
• 6718 S
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726
• 7714 S
• 7715S
• 7716S
• 7718S
• 7720S
• 7722S
• 8650
• 8660
• 8670
• 8680
• 8690
• 8727
• 8730
• 8732
• 8735
• 8737

1. 1

   Check for other active fault codes related to DEF pressure sensors (SPN 4334), DEF pump control (SPN 4375), or DEF tank level/quality (SPN 3361) and resolve them first

2. 2

   Verify the DEF tank is not empty and that the fluid is not frozen (in colder climates)

3. 3

   Test DEF quality using test strips to check for contamination with diesel fuel or oil. If contamination is found, the entire DEF system, including the tank, lines, and pump, will need to be flushed and replaced.

1. 1

   Inspect DEF lines and connections

   Turn the ignition off. Visually inspect all DEF lines between the tank, pump, and dosing module for any signs of damage, pinching, or kinks. Replace any damaged lines. Check all connections to ensure they are secure and that O-rings are not rolled or damaged, which could allow air to enter the system. Inspect the DEF tank vent tube for any blockages or restrictions.

2. 2

   Check for air in the system

   Disconnect the DEF supply line at the dosing unit and place the end into a container of water. Using a diagnostic service tool, perform a DEF system prime or self-check routine. Watch for a continuous stream of air bubbles from the line, which indicates a leak on the suction side (e.g., a cracked supply line or a bad connection at the tank header). If bubbles are present, replace the faulty component.

3. 3

   Inspect for blockages and replace filters

   Remove the DEF tank header and inspect the pickup screen for any debris or crystallized DEF. Replace the main DEF pump filter. This is a common maintenance item and can become clogged with crystals. Inspect and clean or replace the filter screen at the DEF pump inlet and the screen at the dosing unit inlet.

4. 4

   Verify repair and replace DEF pump if necessary

   After performing any repairs, reconnect all lines and electrical connectors. Prime the DEF system using the diagnostic tool's service routine. If the test passes and the code does not return, the issue is resolved. If the system still fails to build pressure or the pump runs erratically after confirming the lines and filters are clear, the DEF pump module has likely failed and requires replacement.