Case IH 3850 – Engine Control Unit (ECU): Zero Fuel Calibration by Lambda (ZFL): DFC reporting error state on comparing energizing time to Min value injector 3.

The Engine Control Unit (ECU) is monitoring the zero-fuel calibration process via the lambda (oxygen) sensor and has detected that the electrical energizing time required for Fuel Injector #3 has dropped below the minimum allowable threshold. This points to either a software calibration mismatch or an internal mechanical defect/wear within the injector itself.

• skid steer
• F5C engine
• F5A engine
• F5G engine
• Farmall 60
• Farmall 75C
• Farmall 115U
• skid steer loaders
• compact track loaders

1. 1

   Connect the CNH Electronic Service Tool (EST) with Easy-Engine software to the machine's diagnostic port

2. 2

   Read the injector codes stored in the ECU and physically inspect Injector #3

3. 3

   Verify that the alphanumeric calibration code programmed into the ECU exactly matches the code printed on the top of Injector #3 (verify cylinder layout in the EST as Injector 3 may correspond to cylinder 4)

4. 4

   Check for any recent ECU flashing or programming errors that might have corrupted the injector calibration data

1. 1

   Reprogram ECU

   If the injector code in the EST does not match the physical injector, reprogram the Engine Control Unit (ECU) with the proper injector code.

2. 2

   Re-flash ECU

   If the codes match but the error persists, try re-flashing the ECU to clear any software corruption.

3. 3

   Determine if injector replacement is needed

   If software calibration and re-flashing do not resolve the issue, the fault is due to an internal defect in the injector.

4. 4

   Depressurize fuel system

   Depressurize the common rail fuel system.

5. 5

   Disconnect injector

   Disconnect the electrical harness and high-pressure fuel line from Injector #3.

6. 6

   Replace injector

   Remove the defective injector and install a new or remanufactured unit, ensuring new copper crush washers and O-rings are used.

7. 7

   Program new calibration code

   Read the new calibration code off the replacement injector and program it into the ECU using the EST. The engine will not run correctly if the new injector is not coded.

8. 8

   Verify repair

   Clear the fault codes and run the engine to verify the repair.