Massey Ferguson 521007.14 – Engine Control Unit (ECU): DEF Pressure Issue (ECU) / DEF Pump/Pressure Issue

The Selective Catalytic Reduction (SCR) system is unable to build, maintain, or read the correct pressure of Diesel Exhaust Fluid (DEF) required for proper injection into the exhaust stream. This usually points to a failure to prime, a blockage caused by urea crystallization, a leak in the supply lines, or a failing DEF supply pump.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724

1. 1

   Visual Inspection: Check the DEF tank for low fluid, frozen fluid, or debris. Ensure the DEF tank vent is clean and not clogged.

2. 2

   Line & Leak Check: Inspect the DEF supply lines for kinks, loose connections, or external leaks. Look for white, crusty urea deposits near the injector nozzle or pump fittings.

3. 3

   Filter Saturation Test: If the system was run dry or sat for a long period, the internal DEF pump filter may have dried out, preventing it from pulling a vacuum.

4. 4

   Pressure Build-Up Test: Using a diagnostic scan tool (like the AGCO EDT), run a 'Pressure Build Up Operation.' Listen for the pump humming. If the pump runs but builds no pressure, disconnect the supply line at the pump, attach a clear 3/8" hose, and route it directly into the DEF tank to see if it can draw fluid directly.

1. 1

   Clean the Inlet Screen

   Remove the DEF pump inlet fitting. This fitting contains a small screen that frequently gets blocked by crystallized DEF. Clean it with warm distilled water (never use tap water, diesel, or solvents, as hydrocarbons will permanently destroy the SCR system).

2. 2

   Re-saturate the Filter

   If the pump filter dried out, allow the DEF pump to sit in DEF fluid overnight to re-saturate the filter. The next morning, run the leak/pressure test three times via the scan tool to see if pressure builds.

3. 3

   Replace the Main DEF Filter

   If the system is still struggling to maintain pressure, replace the main DEF filter cartridge located inside the pump housing.

4. 4

   Replace the DEF Supply Module (Pump)

   If the pump still cannot build pressure after cleaning the inlet screen, replacing the filter, and verifying the supply lines are clear, the internal solenoid membrane pump has failed. Replace the entire DEF Supply Module.

5. 5

   Clear Codes and Retest

   After replacing the parts, use your diagnostic tool to clear the 521007.14 code and run a forced pressure test to verify the system reaches the calibrated pressure range.