Throttle Body

This procedure covers removal and replacement of the throttle body on the 5.9L Cummins diesel engine, which controls airflow into the intake manifold.

Warnings

Tools required

Parts

• Throttle body gasket × 1 — Use OEM specification
• Throttle body assembly (if replacement needed) × 1 — Use OEM specification

Preparation

1. Ensure engine is completely cool
2. Disconnect both batteries (negative terminals first) to prevent electrical issues
3. Allow at least 30 minutes for engine to cool if recently operated
4. Verify replacement throttle body matches original if performing replacement

Procedure

1. 1

   Remove engine cover
   If equipped, remove the plastic engine cover by lifting upward on the cover. It is typically held by rubber grommets that slip over ball studs on the valve cover.
2. 2

   Disconnect air intake system
   Loosen the clamp securing the air intake tube to the throttle body inlet using a flathead screwdriver or 8mm socket. Disconnect the intake tube from the throttle body and move it aside for access.
   Torque spec

   Air Intake Hose Clamps3 Nm (2 lb-ft)
3. 3

   Disconnect electrical connector
   Locate the throttle position sensor (TPS) electrical connector on the side of the throttle body. Press the release tab and disconnect the connector. Note the routing of the wiring harness for reinstallation.
4. 4

   Disconnect vacuum lines
   Identify and disconnect any vacuum lines attached to the throttle body. On most 5.9L Cummins applications, there will be at least one vacuum line for the MAP sensor circuit. Use a shop towel to catch any residual vacuum pump oil if present.
5. 5

   Remove throttle linkage
   Disconnect the throttle cable from the throttle lever by unhooking the cable end from the ball stud on the throttle lever. If equipped with cruise control, disconnect the cruise control cable in the same manner. Slide the cable housing out of the mounting bracket.
6. 6

   Remove throttle body mounting bolts
   Remove the three or four throttle body mounting bolts (depending on model year) using a 10mm socket. Support the throttle body with one hand while removing the final bolt to prevent it from falling.
   Torque spec

   Throttle Body Bolts10 Nm (7 lb-ft)
7. 7

   Remove throttle body and gasket
   Carefully pull the throttle body away from the intake manifold. Remove and discard the old gasket. Use shop towels to cover the open intake manifold port to prevent debris from entering the engine.
8. 8

   Clean mounting surfaces
   Thoroughly clean the throttle body mounting surface on the intake manifold using a soft wire brush or plastic scraper. Remove all old gasket material and carbon deposits. Wipe clean with a shop towel. If reusing the throttle body, clean the throttle bore and plate with throttle body cleaner and allow to dry completely.
   ⚠Do not allow debris to fall into the open intake manifold port. Keep port covered when not actively cleaning the immediate area
9. 9

   Install new gasket
   Remove the shop towels from the intake port. Position the new throttle body gasket onto the intake manifold mounting surface, aligning the bolt holes. Ensure the gasket is properly seated and oriented correctly.
10. 10

    Install throttle body
    Position the throttle body (new or cleaned original) onto the gasket, aligning the bolt holes and throttle shaft. Insert all mounting bolts finger-tight before proceeding to torque them.
    Torque spec

    Throttle Body Bolts10 Nm (7 lb-ft)
11. 11

    Torque throttle body bolts
    Using an inch-pound torque wrench, tighten the throttle body mounting bolts to specification in a crisscross pattern to ensure even seating. Start with the upper bolts and work downward.
    Torque spec

    Throttle Body Bolts10 Nm (7 lb-ft)
12. 12

    Reconnect throttle linkage
    Reconnect the throttle cable and cruise control cable (if equipped) to the throttle lever. Ensure the cable housing is properly seated in the mounting bracket. Verify the throttle lever moves smoothly from idle to full throttle and returns freely to idle position.
13. 13

    Reconnect vacuum lines and electrical
    Reconnect all vacuum lines to their original ports on the throttle body, ensuring they are fully seated. Reconnect the TPS electrical connector until it clicks into place.
14. 14

    Reconnect air intake system
    Reconnect the air intake tube to the throttle body inlet. Ensure the tube is fully seated on the throttle body before tightening the clamp to specification.
    Torque spec

    Air Intake Hose Clamps3 Nm (2 lb-ft)
15. 15

    Reconnect batteries and install engine cover
    Reconnect both battery negative terminals last (negative terminals are the ones that were disconnected). If equipped, reinstall the engine cover by pressing it down onto the mounting grommets.

Reassembly

1. Torque all fasteners to specification using proper torque sequence
2. Ensure all vacuum lines and electrical connectors are fully seated and secure
3. Verify throttle linkage operates smoothly through full range of motion before starting engine

Verification

• Start the engine and verify it idles smoothly without unusual air intake noise or whistling
• Check for vacuum leaks around the throttle body gasket by listening for hissing sounds
• Operate the throttle pedal and verify smooth throttle response without binding or sticking
• Verify no warning lights are illuminated on the instrument cluster related to throttle position sensor
• Check that all vacuum lines remain connected and show no signs of leakage
• If equipped with cruise control, test cruise control function to ensure proper operation

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle