John Deere 3361.05 – Engine Control Unit (ECU): DEF Dosing Injector Circuit Has High Resistance

This code is triggered when the system detects an unusually high electrical resistance in the Diesel Exhaust Fluid (DEF) dosing injector circuit. High resistance typically indicates an open circuit (a broken wire, disconnected plug, or internal failure of the injector coil). This condition prevents sufficient electrical current from reaching the injector, which impairs its ability to accurately dose DEF into the exhaust stream. As a protective reaction, the system may reduce engine power (derate) to manage emissions.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8R / 8RT Series Tractors (8245R to 8400R)
• 9RT Series Track Tractors (9470RT, 9520RT, 9570RT)
• 6M Series Tractors (6105M)
• Various John Deere loaders and backhoes

1. 1

   Inspect the DEF injector wiring harness for physical damage, breaks, loose connections, or corroded contacts that could contribute to high resistance.

2. 2

   Unplug the DEF injector connector and use a multimeter to measure the resistance between the injector terminals (Pins 1 and 2). Compare this reading to the OEM specification (a healthy injector typically reads around 7Ω, though this can vary slightly by specific part number). If the resistance is infinite or out of spec, the injector has failed internally.

3. 3

   If the injector tests good, measure the resistance of the wiring harness from the ECU to the injector connector to check for a broken wire.

4. 4

   Using John Deere Service ADVISOR (or an equivalent diagnostic tool), perform a 'DEF Dosing Test' to see if the ECU can successfully command the injector to fire (e.g., firing the nozzle 33 times) or run a 'DEF High Flow Test' (firing 100 times) to verify functionality.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to ensure the electrical system is safe to work on.

2. 2

   Address Wiring (If Applicable)

   If the diagnostic checks revealed the open circuit is in the wiring harness, repair or replace the damaged section of the harness or the connector.

3. 3

   Remove Faulty Injector

   If the high resistance is internal to the DEF dosing injector, disconnect the DEF fluid line and electrical connector, unbolt the mounting hardware, and remove the faulty injector from the exhaust/SCR system.

4. 4

   Install New Injector

   Install the replacement DEF dosing injector. It is highly recommended to use a new DEF injector mounting gasket to prevent exhaust leaks. Secure it with the mounting screws.

5. 5

   Reconnect

   Reconnect the DEF fluid supply line and the electrical connector to the new injector.

6. 6

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic tool to clear the 003361.05 fault code from the ECU.

7. 7

   System Verification

   Perform a detailed system check using the diagnostic tool (such as the DEF dosing test) or initiate a forced regeneration to ensure the DEF system meets operational specifications and the code does not return.