Massey Ferguson E4354.03 – Engine Control Unit (ECU) / AGCO SISU POWER EEM4: DEF Suction Supply Pipe Heater Relay Issue (ECU)

The DEF suction line heater relay low side (line relay) has an open circuit, or the control circuit is short-circuited to a HIGH SOURCE (battery voltage). The engine controller cannot activate the heater for the suction line, which will eventually cause the engine to enter a derate/power reduction mode.

• 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

   Inspect the main fuse box for blown fuses, specifically the 15A DEF Hose Heating fuse.

2. 2

   Locate the DEF suction line heater relay and swap it with a known good relay to see if the fault clears.

3. 3

   Inspect the wiring harness between the EEM4 ECU and the DEF suction line heater relay for rubbed wires, chafing, or pinched areas causing a short.

4. 4

   Inspect the DEF suction line electrical quick-connectors for corrosion, moisture ingress, or broken pins.

5. 5

   Test the resistance of the heating element inside the DEF suction line to ensure it is not internally open.

1. 1

   Power Down

   Turn off the tractor ignition and disconnect the negative battery cable to prevent electrical spikes.

2. 2

   Resolve Circuit Faults

   If the relay was found to be faulty during diagnostics, replace the DEF suction line heater relay. If the wiring harness is damaged, repair the broken or shorted wires using weather-sealed heat-shrink connectors. If the heating element inside the DEF suction line is open/burnt out, the entire DEF suction line hose assembly must be replaced.

3. 3

   Reassemble

   Reconnect all DEF line electrical connectors, ensuring the O-rings and locking tabs are secure to prevent air ingress or fluid leaks. Reconnect the battery.

4. 4

   Clear Codes

   Save the error log using a diagnostic service tool (like WinEEM4), and then erase the error log.

5. 5

   ECU Reset

   Restart the ECU after erasing the log. Turn the ignition off for a minimum of 60 seconds, then turn it back on (System Reset).

6. 6

   Verify

   Start the tractor and verify that the warning lamp is deactivated and the fault code does not return.