New Holland ENG 3666 – Engine ECU: EGR Permanent Governor Deviation for Valve

The actual physical position of the Exhaust Gas Recirculation (EGR) valve does not match the target position commanded by the engine controller. This is most commonly a mechanical issue where heavy soot and carbon buildup has jammed the valve, preventing it from opening or closing fully, though it can also indicate a failure of the valve's internal electronic actuator motor.

• L216
• L220
• L230
• L328
• C238
• C327
• T4 Series
• T4.55

1. 1

   Check for Accompanying Electrical Codes: Verify if other EGR-related codes are present (e.g., 3667, 3668, 3669–3672) to rule out an electrical or wiring failure.

2. 2

   Wiring and Connector Inspection: Inspect the wiring harness leading to the EGR valve for chafed wires, melted insulation, or corrosion inside the connector pins.

3. 3

   Visual/Mechanical Inspection: Remove the EGR valve and inspect the pintle/flap for heavy carbon and soot buildup indicating it is physically jammed.

1. 1

   Safety First

   Park the machine on a level surface, turn off the engine, and disconnect the negative battery cable to prevent electrical shorts. Allow the engine and exhaust components to cool completely.

2. 2

   Locate the Valve

   Locate the EGR valve assembly, which is typically mounted near the exhaust manifold and EGR cooler on the F5C/F5H engine block.

3. 3

   Disconnect Electricals

   Depress the locking tab and disconnect the electrical harness connector from the EGR valve actuator.

4. 4

   Remove the Valve

   Remove the mounting bolts securing the EGR valve to the manifold/cooler housing.

5. 5

   Clean the Mating Surface

   Carefully remove the old metal gasket. Use a plastic scraper and solvent to clean the mating surface on the engine side. Caution: Ensure no carbon chunks or old gasket material fall into the intake or exhaust passages.

6. 6

   Install the New Part

   Position the new EGR valve with a new OEM gasket. Thread the mounting bolts by hand to prevent cross-threading.

7. 7

   Torque to Spec

   Tighten the mounting bolts to the OEM torque specifications outlined in your specific machine's service manual.

8. 8

   Reassembly

   Reconnect the electrical harness connector until it clicks securely. Reconnect the battery.

9. 9

   Clear Codes and Test

   Use a diagnostic scan tool (or Can-Bus Eraser) to clear the ENG 3666 fault code from the Engine ECU. Start the engine, allow it to reach operating temperature, and verify that the code does not return under load.