Massey Ferguson E520225.31 – Engine Control Unit (ECU): Engine Module Internal Issue / MOCSOP (redundant stop test) Diagnostic error

The engine controller failed its internal self-diagnostic check regarding the redundant engine stop circuit, indicating an internal hardware or software processing error within the module itself.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• MF 5608
• MF 5609
• MF 5610
• MF 5611
• MF 5612
• MF 5613
• MF 7614
• MF 7615
• MF 7616
• MF 7618
• MF 7619
• MF 7620
• MF 7622
• MF 7624
• MF 7626

1. 1

   Check battery and charging system to ensure correct voltage output, as voltage spikes or drops can cause the ECU's internal self-tests to fail.

2. 2

   Inspect ECU power and ground circuits, including the main power relays and ground straps connected to the engine ECU.

3. 3

   Inspect the wiring harness by disconnecting the ECU and checking the pins for corrosion, moisture ingress, or damage.

4. 4

   Check for accompanying codes (e.g., E520228.12 - Module multiple supply error). If present, troubleshoot the power supply issue first.

5. 5

   Use a diagnostic tool to clear the code and retest. If caused by a transient software glitch during shutdown/startup, it may not return. If it is a hard fault, it will return immediately upon key-on or engine crank.

1. 1

   Turn off the ignition and disconnect the tractor's negative battery cable.

2. 2

   Locate the Engine ECU.

   Typically mounted on the side of the engine block.

3. 3

   Carefully release the locking levers on the ECU harness connectors and unplug them.

4. 4

   Unbolt the ECU from its mounting bracket.

5. 5

   Install the replacement ECU and secure the mounting bolts.

6. 6

   Reconnect the wiring harnesses.

   Ensure the locking levers click fully into place.

7. 7

   Reconnect the negative battery cable.

8. 8

   Program the new or remanufactured ECU.

   Flash with the correct firmware for your specific tractor model and engine configuration using an AGCO diagnostic tool.

9. 9

   Clear any residual fault codes and run the engine.

   Verify the redundant stop test passes and the code does not return.