John Deere 003361.07 – ECU: DEF Injector Actuation Failure

The Engine Control Unit (ECU) has detected that the Diesel Exhaust Fluid (DEF) dosing injector is not actuating correctly when commanded, failing to open or close properly. This malfunction is typically caused by a mechanical seizure due to DEF crystallization (stuck open or closed) or an internal failure of the injector's actuating mechanism. This fault will trigger warning lights and can lead to a reduction in engine power to ensure compliance with emissions regulations.

• 6R Series
• 7R Series
• 8R Series
• G-Series Skid Steers
• P-Series Loaders
• G-Series Excavators
• PowerTech 4.5L

1. 1

   Visually inspect the DEF injector, wiring harness, and surrounding area for DEF leakage, white crystal deposits around the injector nozzle and its mounting point, damaged wires, or corrosion on the electrical connector, particularly within the first few inches of the connector.

2. 2

   Check DEF quality visually (should be clear and colorless with a faint ammonia smell) and use a DEF refractometer (JDG11594 or JDG11684) to ensure urea concentration is between 31.8% and 33.2%.

3. 3

   Perform a resistance check on the injector terminals (typically 2 to 10 ohms) to check for internal electrical failure.

4. 4

   Check for voltage at the injector's wiring harness connector with the ignition on to confirm it is receiving power from the ECU.

5. 5

   Use a diagnostic scan tool to perform an Injector Actuation Test (listen for an audible click) and a Flow/Spray Pattern Test (expect 40-55ml over 2 minutes with a proper cone-shaped spray).

1. 1

   Ensure safety and access injector

   Park the machine on a level surface, turn off the engine, allow the exhaust system to cool completely, and disconnect the battery. Locate the DEF injector mounted on the exhaust pipe upstream of the SCR catalyst, removing heat shields if necessary.

2. 2

   Remove the DEF injector

   Disconnect the electrical connector and the DEF fluid line. Use a cloth to absorb residual fluid and clean spills immediately with water, as DEF is corrosive. Remove the mounting bolts or retaining clamp and carefully remove the injector. It may be stuck due to carbon and crystal buildup, requiring gentle persuasion to free it.

3. 3

   Clean and inspect mounting surface

   Clean the injector mounting port on the exhaust pipe to ensure a good sealing surface for the new or cleaned injector.

4. 4

   Clean or replace the injector

   If mildly clogged with crystals, soak the nozzle in warm distilled water and gently clean with a soft brush (no metal tools), then flow test. If heavily crystallized, physically damaged, or failing electrical tests, replace the injector.

5. 5

   Install injector

   Install the new or cleaned injector with a new gasket or seal. Tighten the mounting bolts to the manufacturer's specified torque and reconnect the DEF fluid line and electrical connector.

6. 6

   Finalize repair

   Reconnect the battery. Using a diagnostic scan tool, prime the DEF system to ensure fluid is supplied. Start the engine, check for leaks at the fluid line and exhaust mounting point, clear the fault codes, and run the machine to ensure the fault does not return. Some systems may require a specific 'first start' or 'learning' procedure after component replacement, which would be detailed in the service manual.