Massey Ferguson 3363.31 – Engine ECU (AGCO SISU POWER EEM4): DEF Tank Heater Solenoid Valve High Voltage (ECU) / DEF tank heater ECU power stage over temperature

The engine controller has detected an over-temperature condition or a high-voltage short on the internal power stage circuit that supplies voltage to the DEF tank heater coolant valve solenoid. This is usually caused by excessive current draw from a shorted solenoid valve or a short circuit in the wiring harness.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4707
• 4708
• 4709
• 4710
• 5710 SL
• 5711 SL
• 5712 SL
• 5713 SL
• 7714
• 7715
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720
• 7720S
• 7722
• 7722S
• 7724
• 7724S
• 7726
• 7726S

1. 1

   Check for accompanying codes such as SPN 3363 FMI 3 (short to high source), FMI 4 (short to ground), or FMI 5 (open circuit) to pinpoint the wiring fault

2. 2

   Visually inspect the wiring harness running from the Engine ECU (EEM4) to the DEF tank heater coolant valve solenoid for chafed wires, melted insulation, or pinch points

3. 3

   Disconnect the harness at the DEF tank heater valve and at the ECU to inspect the pins for corrosion, moisture intrusion, or bent terminals

4. 4

   Using a multimeter, measure the internal resistance of the DEF tank heater coolant valve solenoid to check for a dead short or extremely low ohms

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative battery cable to prevent further damage to the ECU.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a short in the wiring harness, repair the damaged section of the wire or replace the affected harness pigtail. Ensure all splices are sealed against moisture.

3. 3

   Replace the Solenoid

   If the DEF tank heater coolant valve solenoid failed the resistance test, remove the defective valve from the coolant lines routing to the DEF tank. Install the new valve and secure the coolant hoses.

4. 4

   Address the ECU

   If the wiring and solenoid test perfectly fine but the code remains active, the Engine ECU will need to be replaced or sent out for repair.

5. 5

   Clear Codes and Test

   Reconnect the battery. Use an AGCO/Massey Ferguson compatible diagnostic service tool to clear the fault codes. Run the engine and monitor the DEF system to ensure the code does not return and the DEF tank heater operates normally.