Massey Ferguson 2659.01 – Engine Control Unit (ECU): EGR Gas Flow Issue (ECU) / NOx-Based EGR Flow Correction Extremely Low

The Engine Control Unit (ECU) has detected that the actual Exhaust Gas Recirculation (EGR) mass flow rate is significantly lower than the commanded/expected flow. Specifically, the NOx-based EGR flow correction factor has reached its minimum threshold, indicating that tailpipe NOx emissions may be out of compliance. This is most commonly caused by heavy soot (unburnt fuel) deposits restricting the EGR valve or plugging the EGR cooler, often due to prolonged "light loading" engine operation.

• 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
• 5709
• 5710
• 5712
• 5713
• 6711
• 6712
• 6713

1. 1

   Check for Associated Fault Codes: Use a diagnostic tool to check for other active codes (e.g., SPN 2791 for EGR Valve Internal/Communication issues). If electrical or sensor codes are present, address those first.

2. 2

   Inspect Wiring and Connectors: Check the wiring harness and connectors at the EGR valve and the Exhaust Back Pressure / Delta P sensors. Look for damaged wires, corroded terminals, or loose pins.

3. 3

   Perform an EGR Operational Test: Using a diagnostic tool, command the EGR valve to open and close. Monitor the Mass Air Flow (MAF) or EGR Delta P voltage to verify that the flow actually changes when the valve is commanded ON.

4. 4

   Inspect for Soot Blockages: Remove the EGR differential pressure sensor from its mounting pad and inspect the ports and tubes for heavy soot buildup or blockages.

1. 1

   Clean Pressure Ports

   If soot is found in the EGR differential pressure ports or tubes, carefully clean and clear the passages. This simple maintenance step often restores proper sensor readings and clears the code.

2. 2

   Inspect/Replace the EGR Valve

   If the EGR valve is stuck closed due to heavy soot deposits or fails the operational test, remove the valve. While cleaning is sometimes attempted, OEM procedures often recommend replacing a heavily fouled or mechanically stuck EGR valve.

3. 3

   Inspect/Replace the EGR Cooler

   If the valve is functioning but flow is still low, the EGR cooler is likely plugged with soot. Depending on the severity, the cooler core will need to be replaced (modern OEM procedures often advise replacing the low-temp core rather than attempting to clean it).

4. 4

   Reassemble and Verify

   Install the new components, ensuring all coolant lines and electrical connectors are securely fastened.

5. 5

   Clear Codes and Test

   Use the diagnostic tool to clear the 002659.01 fault code. Start the engine, bring the coolant temperature above 65°C (149°F), and perform a test drive under load to verify the code does not return.