Massey Ferguson 521007.1 – ECU: DEF Pressure Issue

The engine's aftertreatment system is detecting an abnormal pressure condition (either too high, too low, or erratic) within the Diesel Exhaust Fluid (DEF) dosing system, preventing proper NOx conversion.

• 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
• 4700 Series
• 5600 Series
• 7600 Series
• 7700 Series
• 8700 Series

1. 1

   Verify the DEF tank is full of fresh, unexpired DEF (32.5% high-purity urea) to rule out contamination.

2. 2

   Inspect all DEF lines and the dosing injector nozzle for cracked lines or a buildup of white, crusty deposits indicating a leak or poor atomization.

3. 3

   Turn the key on and listen for the DEF pump priming. It should produce a steady humming sound; a loud, erratic, or silent pump indicates internal damage or electrical failure.

4. 4

   Verify the power supply (voltage and ground) to the DEF pump and the DEF pressure sensor.

5. 5

   Use diagnostic software to monitor the DEF pressure sensor readings in real-time to see if the sensor is reading out of range or if the pump is failing to build pressure.

1. 1

   Drain and Flush

   If contamination is suspected, completely drain the DEF tank and flush the lines before introducing new fluid.

2. 2

   Replace the DEF Filter

   Locate the DEF pump assembly and replace the internal/external DEF filter element to resolve restricted flow.

3. 3

   Clean the Dosing Valve

   Remove the DEF injector nozzle at the exhaust catalyst and clean any crystallized urea buildup using warm water.

4. 4

   Replace the Sensor or Pump

   If diagnostics show the pump is building pressure but the sensor reads zero, replace the DEF Pressure Sensor. If the pump is making abnormal noises, leaking, or failing to build pressure, replace the DEF Supply Pump/Dosing Module.

5. 5

   Clear Codes and Prime

   After replacing the faulty parts, use a diagnostic tool to clear the 521007.10 code. Run a manual DEF dosing test or a forced regeneration to prime the system and verify that proper pressure is maintained.