Knock Sensor

This procedure covers the removal and replacement of the knock sensor on a 2014 Ram 2500 with the 6.7L Cummins diesel engine, which requires accessing the sensor from beneath the vehicle.

Warnings

Tools required

Parts

• Knock sensor × 1 — Use OEM Mopar specification
• Knock sensor wiring harness (if damaged) × 1 — Use OEM specification

Preparation

1. Park the vehicle on a level surface and engage the parking brake
2. Place wheel chocks behind the rear wheels
3. Allow the engine to cool completely (minimum 2 hours after operation)
4. Disconnect the negative battery cable to prevent electrical shorts
5. Safely raise and support the front of the vehicle on jack stands rated for the vehicle weight
6. Remove the factory skid plate/belly pan if equipped to access the engine from below

Procedure

1. 1

   Locate the knock sensor
   From underneath the vehicle, locate the knock sensor on the driver's side of the engine block, approximately mid-way along the block length, below and slightly behind the fuel filter housing. The sensor will have a single wire connector attached.
2. 2

   Disconnect the knock sensor electrical connector
   Press the release tab on the electrical connector and carefully pull it away from the knock sensor. If the connector is difficult to remove due to corrosion, apply penetrating oil and wait 5-10 minutes. Inspect the connector pins for corrosion or damage.
3. 3

   Clean the sensor area
   Use a wire brush or compressed air to remove dirt and debris from around the knock sensor mounting boss on the engine block. This prevents contamination from entering the sensor bore during removal.
4. 4

   Remove the knock sensor
   Using a socket and extension, carefully remove the knock sensor by turning counterclockwise. The sensor may be tight due to heat cycling. Apply gentle, steady pressure to avoid stripping the threads. If the sensor is seized, apply penetrating oil and allow it to soak for 15-20 minutes before attempting removal again.
   ⚠Do not use excessive force or impact tools. The aluminum threads in the engine block can be easily damaged.
5. 5

   Inspect the sensor bore
   Once the sensor is removed, inspect the threaded bore in the engine block for damage, debris, or corrosion. Clean the threads with a wire brush if necessary. Check the old sensor for damage to the threads or sensing element. Verify the electrical connector on the sensor is intact.
6. 6

   Prepare the new knock sensor
   Remove the new knock sensor from its packaging. Verify it matches the old sensor design. Check that the threads are clean and undamaged. Do not apply any anti-seize compound or thread sealant unless specifically required by the manufacturer - the sensor must have proper electrical ground contact with the block.
7. 7

   Install the new knock sensor
   Thread the new knock sensor into the engine block by hand, turning clockwise. Ensure the sensor threads in smoothly without resistance. Thread it in until it is hand-tight and seated against the mounting surface.
   ⚠Start the sensor by hand to ensure cross-threading does not occur. If resistance is felt, back out and restart.
8. 8

   Torque the knock sensor
   Using a calibrated torque wrench, tighten the knock sensor to the specified torque. Apply torque in a smooth, steady motion. Do not exceed the specified torque value as this is critical for proper sensor function and can damage the piezoelectric element inside the sensor.
   Torque spec

   Knock Sensor20 Nm (15 lb-ft)
9. 9

   Reconnect the electrical connector
   Push the electrical connector onto the knock sensor until it clicks into place. Gently tug on the connector to verify it is fully seated and locked. Ensure the wiring harness is routed away from hot exhaust components and sharp edges.
10. 10

    Reinstall protective covers
    If the factory skid plate or belly pan was removed, reinstall it using the original hardware. Ensure all fasteners are properly tightened.
11. 11

    Lower the vehicle and reconnect the battery
    Carefully lower the vehicle from the jack stands. Reconnect the negative battery cable and tighten the terminal connection.

Reassembly

1. Ensure the knock sensor electrical connector is fully seated and locked
2. Verify all skid plates and protective covers are reinstalled securely
3. Double-check that no tools or parts were left in the engine compartment or underneath the vehicle

Verification

• Start the engine and verify it runs smoothly without any warning lights on the instrument cluster
• If a check engine light was present before the repair, use a diagnostic scan tool to clear codes and verify the knock sensor is reading properly
• Monitor for diagnostic trouble codes related to the knock sensor (P0325, P0326, P0327, P0328) after test driving
• Perform a brief test drive and verify normal engine operation without audible knocking or pinging under acceleration
• Re-check the sensor area from underneath for any fluid leaks or loose connections after the test drive

More procedures for this vehicle