Massey Ferguson 3361.05 – Engine ECU: DEF Injector High Resistance / DEF Dosing Valve High Side Short Circuit to High Source or Open Load.

The Engine Control Unit has detected that the electrical resistance in the DEF (Diesel Exhaust Fluid) dosing injector circuit is too high. This almost always indicates an open circuit, meaning there is a broken wire, a disconnected plug, or the internal electromagnetic coil within the DEF injector has failed and broken continuity.

• 4710
• 7724S
• 5712SL
• Interim Tier 4 (2012-2015)
• 7722
• 7722S
• 7615
• 5613
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 7616
• 7618
• 5608
• 4708
• 7619
• 7626
• 7726S
• 7624
• 4707
• 4709
• 5711SL
• 7614
• 7718S
• 5610
• 7620
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 5612
• 7622
• 7720
• Tier 4 (2015-2021)
• 5611
• 7715S
• 5609
• 7724
• 5710 SL
• 5711 SL
• 5712 SL
• 5713 SL

1. 1

   Visual Inspection: Inspect the wiring harness leading to the DEF dosing valve for chafing, breaks, or melted sections caused by exhaust heat.

2. 2

   Connector Check: Disconnect the DEF injector plug and check for corrosion, pushed-back pins, or DEF fluid intrusion (DEF is highly corrosive to wiring).

3. 3

   Component Resistance Test: Use a multimeter to measure the resistance across the pins of the DEF injector itself. If the reading shows an open circuit (infinite resistance/OL), the injector has failed internally and must be replaced.

4. 4

   Harness Continuity Test: If the injector tests within spec, measure continuity from the injector connector back to the Engine ECU pins to locate the break in the main harness.

1. 1

   Wait for Purge Cycle

   Turn off the tractor ignition and wait at least 5 to 10 minutes before disconnecting any lines. The DEF system must complete its automatic purge cycle to return fluid to the tank. Disconnecting lines while under pressure will cause DEF to spray.

2. 2

   Disconnect Electrical

   Unplug the electrical connector from the DEF dosing valve.

3. 3

   Disconnect Lines

   Carefully remove the DEF supply line and the coolant lines (if the doser is coolant-heated). Cap or pinch the coolant lines to prevent fluid loss.

4. 4

   Remove Injector

   Unbolt the DEF injector from the exhaust mixing pipe / SCR catalyst inlet.

5. 5

   Clean the Port

   Clean the mounting surface on the exhaust pipe. Ensure no crystallized DEF buildup or old gasket material remains, as this will cause exhaust leaks.

6. 6

   Install New Part

   Mount the new DEF injector using a new sealing gasket/clamp. Torque the mounting hardware to OEM specifications.

7. 7

   Reconnect

   Reattach the DEF fluid line, coolant lines, and electrical connector.

8. 8

   Clear Codes & Test

   Use a diagnostic service tool to clear the 003361.05 fault code. Run a forced DEF dosing test or perform a test drive to ensure the SCR system is functioning correctly and no leaks are present.