Massey Ferguson 4332.16 – Engine ECU (EEM4): DEF System Pressure Issue / SCR system ERROR: DEF dosing pressure above normal.

The engine monitoring system has detected that the pressure during the metering control phase is too high inside the DEF (Diesel Exhaust Fluid) supply module. This typically triggers an emissions-related warning lamp and will eventually result in an engine power derate (reduced power/speed) if not addressed.

• 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

   Check the DEF backflow line for physical damage, kinks, or internal blockages.

2. 2

   Check the DEF supply module backflow connector to ensure it is not blocked by crystallized DEF.

3. 3

   Inspect the DEF supply module main filter for defects or severe clogging.

4. 4

   Check DEF fluid quality to ensure it is not contaminated, degraded, or frozen.

5. 5

   Perform a module substitution test with a known-good DEF supply module to verify if the original pump's internal pressure sensor or valving has failed.

1. 1

   Clear the Error Log

   Connect your diagnostic tool, save the error log, and erase the active codes. Restart the ECU (key cycle). If the fault returns during the next driving cycle, proceed to physical repairs.

2. 2

   Clean the Lines

   Disconnect the DEF backflow lines and flush them with warm distilled water to dissolve any crystallized urea blockages.

3. 3

   Replace the DEF Filter

   Remove the DEF supply module main filter housing cap, extract the old filter element, clean the housing of any debris, and install a new filter and O-ring.

4. 4

   Replace the DEF Supply Module

   If the lines are clear and a new filter does not resolve the over-pressure condition, the DEF supply module (pump) is defective. Disconnect the electrical harness and fluid lines, unbolt the module, and install the replacement unit.

5. 5

   System Prime and Test

   Turn the key on to allow the new pump to prime the system. Run an SCR system pressure test via the diagnostic tool to ensure dosing pressure is now within normal parameters.