New Holland ENG 3975 – Engine ECU: Intake Throttle Stuck Error

Indicates that the engine's intake throttle valve actuator is physically binding, stuck open/closed, or failing to reach its commanded position.

• L218
• L220
• L228
• L318
• C-Series
• Case SR175
• Case SV185

1. 1

   Check for related electrical codes such as 3972 (Intake Throttle Motor Driver Circuit Invalid) which would point to a wiring issue rather than a mechanical bind.

2. 2

   Remove the intake piping to the throttle valve and inspect for heavy soot, carbon buildup, or foreign debris that could cause the butterfly valve to stick.

3. 3

   Inspect the wiring harness leading to the intake throttle actuator for chafed wires, short circuits, or corroded pins.

4. 4

   Verify that the Engine ECU is outputting the correct 5V reference signals to the engine sensors (check for codes 1011, 1012, 1013, or 1014 which indicate 5V reference circuit faults).

1. 1

   Access the Valve

   Turn off the machine, disconnect the battery, and locate the intake throttle valve on the engine's intake manifold plumbing.

2. 2

   Remove and Clean

   Disconnect the electrical connector and remove the mounting bolts. If the valve is stuck due to carbon/soot buildup (common in EGR-equipped diesel engines), thoroughly clean the valve body and butterfly plate using an appropriate EGR/throttle body solvent.

3. 3

   Actuator Test

   If the valve is clean but still mechanically binds, or if the internal electronic motor/position sensor has failed, the unit cannot be repaired and must be replaced.

4. 4

   Install New Part

   Install the new intake throttle valve, torque the mounting bolts to OEM spec, and reconnect the electrical harness.

5. 5

   Clear Codes

   Use the Electronic Service Tool (EST) or a compatible heavy-duty DTC eraser to clear the fault codes from the Engine ECU.