Case IH 3850 – ENGINE ECU (EDC - Electronic Diesel Control module): Zero Fuel Calibration by Lambda (ZFL): DFC reporting error state on comparing energizing time to Min value injector 3

The Engine Control Unit (ECU) performs a "Zero Fuel Calibration" (ZFL) using the Lambda (oxygen) sensor to monitor the exact energizing time required for the fuel injector to deliver fuel. For Injector 3, the Diagnostic Fault Check (DFC) is reporting an error state because the energizing time compared to the minimum allowed value is out of range. This indicates an issue with the mechanical response of Injector 3, fuel delivery, or the injector circuit.

• Farmall
• F5C engine series
• F5H engine series
• NEF engine series
• SR175
• SR200
• SR220
• SR250
• SV250
• SV300
• TR270
• TR320
• TV380
• Farmall 115U Pro EP

1. 1

   Check for air ingress by installing a clear test line at the fuel inlet to observe for air bubbles entering the fuel supply

2. 2

   Check fuel pressure from the gear supply (lift) pump (pressure should not drop below 0.276 bar / 4.0 psi or 5 bar / 72 psi minimum depending on the test point)

3. 3

   Inspect primary and secondary fuel filters for restrictions or clogs

4. 4

   Check the fuel leakage rate from the electronically controlled injectors to isolate excessive leakage from Injector 3

5. 5

   Check the wiring harness and connectors for Cylinder 3 Injector for open or short circuits

1. 1

   Resolve Fuel Supply Issues

   If restrictions or air leaks were found during diagnostics, replace the primary and secondary fuel filters and repair any compromised fuel lines.

2. 2

   Bleed the System

   Bleed the fuel system to ensure no air remains in the lines.

3. 3

   Replace the Injector

   If fuel pressure is adequate, wiring is intact, and the code persists, the mechanical response of Injector 3 has failed. Remove and replace the fuel injector for Cylinder 3.

4. 4

   Reprogram the ECU

   After replacing the injector, you must use the appropriate Case IH Electronic Service Tool (EST) to write the correct new injector codes to the Engine Controller. This restores the ECU's self-learning parameters and clears the calibration error.