Massey Ferguson 4357.04 – ECU: DEF Injector Supply Heater Resistance Is Low

The control module has detected that the electrical resistance in the DEF injector supply line's heater circuit has dropped below the minimum acceptable threshold. This almost always indicates a short circuit—either a short to ground in the tractor's wiring harness or a shorted/melted heating element inside the DEF supply line itself.

• 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
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726

1. 1

   Visually inspect the DEF injector supply line for pinched areas, melted insulation from exhaust heat, or chafing against the chassis.

2. 2

   Disconnect the electrical connector for the DEF supply line heater and inspect the pins for water ingress, corrosion, or melting.

3. 3

   Measure the resistance across the heater pins directly on the DEF supply line using a multimeter (a reading near 0 ohms indicates a shorted internal heating element).

4. 4

   Measure the resistance of the wiring harness from the ECU to the heater connector and check for continuity to ground to ensure the short isn't in the main harness.

5. 5

   Inspect the DEF supply module heater relay to ensure the contacts haven't fused closed.

1. 1

   Disconnect battery

   Turn off the tractor, remove the key, and disconnect the negative battery terminal.

2. 2

   Locate supply line

   Locate the DEF injector supply line routing from the DEF tank/pump module to the DEF doser/injector on the exhaust.

3. 3

   Disconnect heater connector

   Disconnect the electrical connector for the supply line heater.

4. 4

   Release fluid fittings

   Release the quick-connect fluid fittings at both ends of the supply line. Note: Have a catch pan ready. Clean any spilled DEF immediately with warm water, as it is highly corrosive to metal and wiring.

5. 5

   Remove supply line

   Unclip the supply line from its routing brackets and remove it from the tractor.

6. 6

   Route new supply line

   Route the new heated DEF supply line into position. Ensure it is secured in its factory brackets and kept away from sharp edges or direct exhaust heat to prevent future melting/chafing.

7. 7

   Connect fluid fittings

   Snap the quick-connect fluid fittings into place until they click securely.

8. 8

   Reconnect heater connector

   Reconnect the electrical connector for the heater.

9. 9

   Reconnect battery

   Reconnect the battery.

10. 10

    Clear fault code

    Use an AGCO EDT (Electronic Diagnostic Tool) or compatible scan tool to clear the 004357.04 fault code.

11. 11

    Test DEF system

    Run the engine and perform a DEF system pressure/dosing test via the scan tool to prime the system and verify there are no leaks at the quick-connect fittings.