Massey Ferguson E520213.31 – Engine Control Unit (ECU): Engine Module Internal Issue (ECU) / MOCSOP (redundant stop test) Diagnostic error

The engine controller failed its internal self-diagnostic test of the redundant shut-off paths (the internal safety circuits designed to shut the engine down in an emergency).

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

1. 1

   Verify that the battery voltage is stable, as undervoltage or severe voltage spikes during cranking can cause the MOCSOP self-test to fail or time out.

2. 2

   Inspect the main engine harness, specifically the power (+12V) and ground (-) pins at the Engine ECU connectors, and ensure the main ECU relays are functioning correctly without short circuits.

3. 3

   Check the ECU connectors for moisture intrusion, corrosion, or backed-out pins, which can cause internal logic errors.

4. 4

   Clear the fault code using a diagnostic tool and cycle the ignition key to see if the MOCSOP test passes on a clean boot. If it passes, the issue may have been a transient voltage glitch.

1. 1

   Disconnect Power

   Disconnect the negative terminal of the tractor's battery.

2. 2

   Remove the ECU

   Locate the Engine ECU mounted on the side of the engine block. Carefully release the locking levers on the wiring harness connectors and unplug them. Unbolt the ECU from its vibration-damping mounts.

3. 3

   Install the New ECU

   Mount the replacement ECU to the engine block and reconnect the wiring harnesses, ensuring the locking levers are fully seated.

4. 4

   Dealer Programming

   An authorized Massey Ferguson/AGCO dealer must connect the AGCO EDT (Electronic Diagnostic Tool) to flash the correct engine software, input the tractor's specific ID module data, and code the fuel injector trim files.

5. 5

   Final Testing

   Reconnect the battery, turn the key to the ON position to allow the new ECU to perform its MOCSOP self-test, and verify that the E520213.31 code does not return. Start the engine to confirm the repair.