Remove and replace the knock sensor on the electric drive unit of a 2023 Chevrolet Bolt EUV, requiring removal of protective covers and electrical connections to access the sensor mounted on the drive unit housing.

Warnings

Tools required

Parts

• Knock sensor × 1 — Use OEM specification
• Drive unit access cover gasket × 1 — Use OEM specification
• Electrical connector seal × 1 — Inspect and replace if damaged

Preparation

1. Park vehicle on level surface and engage parking brake
2. Place wheel chocks behind rear wheels
3. Ensure vehicle is powered off and key fob is at least 20 feet away
4. Open hood and locate 12V battery in engine compartment
5. Disconnect negative (-) terminal of 12V battery and isolate cable
6. Wait minimum 5 minutes for electrical systems to discharge
7. Lift front of vehicle and secure on jack stands rated for vehicle weight
8. Remove front driver side wheel for access to drive unit area
9. Remove lower splash shield and underbody panels as needed for access

Procedure

1. 1

   Remove drive unit protective cover
   Locate the protective cover on the driver side of the electric drive unit. Remove the cover bolts in a cross pattern to prevent warping. Carefully remove the cover and set aside with hardware.
   Torque spec

   Cover Bolts16 Nm (12 lb-ft)
2. 2

   Disconnect wiring harness from drive unit area
   Identify the wiring harness routing near the knock sensor location. Release any wire harness clips or retainers securing the harness to the drive unit. Carefully move harness aside to provide working clearance.
3. 3

   Access knock sensor through service opening
   Locate the service gasket cover on the drive unit housing that provides access to the knock sensor mounting location. Remove gasket bolts in sequence and carefully remove the access cover. Inspect gasket condition and plan for replacement.
   ⚠Small amount of lubricant may be present. Have shop towels ready to catch any drips.
   Torque spec

   Gasket Bolts20 Nm (15 lb-ft)
4. 4

   Disconnect knock sensor electrical connector
   Locate the knock sensor electrical connector. Press the locking tab and carefully disconnect the connector from the sensor. If connector bolts are present, remove them first. Inspect connector pins for damage or corrosion.
   Torque spec

   Electrical Connector Bolts7 Nm (5 lb-ft)
5. 5

   Remove knock sensor
   Using appropriate socket, carefully loosen the knock sensor. Note the orientation and position of the sensor for installation reference. Remove sensor completely from the drive unit housing. Inspect the sensor mounting boss for damage or debris.
   ⚠Do not drop the sensor or allow it to impact hard surfaces as this will damage the piezoelectric element inside.
6. 6

   Clean sensor mounting location
   Thoroughly clean the knock sensor mounting boss on the drive unit housing using cleaning solvent and lint-free towels. Remove all old thread sealant, oil residue, or debris. The mounting surface must be completely clean and dry for proper sensor function. Inspect threads for damage.
   ⚠Do not use wire brushes or abrasive tools that could damage the precision mounting surface.
7. 7

   Test new knock sensor
   Before installation, verify the new knock sensor is functioning properly using a digital multimeter. Check resistance across sensor terminals - typical reading should be between 3.5-4.5 megohms at room temperature (consult service manual for exact specification). Inspect sensor threads and mounting surface.
8. 8

   Install new knock sensor
   Thread the new knock sensor into the drive unit housing by hand to ensure proper thread engagement. Once hand-tight, use torque wrench to tighten to specification in one smooth motion. Do not over-tighten. Verify sensor is seated flush against mounting surface.
   ⚠Torque specification is critical - use calibrated torque wrench and tighten to exactly 20 Nm (15 lb-ft). This ensures proper sensor contact and signal quality.
9. 9

   Reconnect knock sensor electrical connector
   Apply small amount of dielectric grease to connector terminals if recommended by manufacturer. Align connector with sensor and press firmly until locking tab clicks. If connector mounting bolts are present, install and torque to specification. Gently tug connector to verify secure connection.
   Torque spec

   Electrical Connector Bolts7 Nm (5 lb-ft)
10. 10

    Clean gasket mating surfaces
    Thoroughly clean both the drive unit housing gasket surface and the access cover gasket surface. Remove all old gasket material and oil residue using approved cleaning solvent. Surfaces must be completely clean and dry for proper seal. Inspect for damage or warping.
    Torque spec

    Gasket Surface Bolts20 Nm (15 lb-ft)
11. 11

    Install new access cover gasket
    Position new gasket on the drive unit housing, ensuring proper alignment with all bolt holes. Place access cover over gasket and start all gasket bolts by hand. Tighten bolts in a cross pattern to specified torque to ensure even gasket compression and prevent leaks.
    ⚠Follow cross-pattern tightening sequence to prevent gasket distortion and ensure proper seal.
    Torque spec

    Gasket Bolts20 Nm (15 lb-ft)

    Gasket Surface Bolts20 Nm (15 lb-ft)
12. 12

    Reinstall wiring harness
    Route wiring harness back to original position, ensuring no pinch points or interference with moving components. Secure harness with all original clips and retainers. Verify adequate clearance and no tension on knock sensor connector.
13. 13

    Reinstall drive unit protective cover
    Position protective cover over drive unit and align all mounting holes. Install cover bolts and tighten in cross pattern to specification. Verify cover is properly seated and all mounting points are secure.
    Torque spec

    Cover Bolts16 Nm (12 lb-ft)
14. 14

    Reinstall underbody components and wheel
    Reinstall all underbody panels and splash shields that were removed for access. Install driver side front wheel and torque lug nuts to manufacturer specification (typically 140 Nm/103 lb-ft). Lower vehicle from jack stands.
15. 15

    Reconnect battery and clear codes
    Reconnect negative terminal of 12V battery and tighten securely. Power on vehicle and verify no warning lights related to drive unit or sensor malfunction. Use diagnostic tool to clear any stored fault codes related to knock sensor. Record any active codes before clearing.
    ℹ️Some fault codes may require a drive cycle to clear completely.

Reassembly

1. All components should be reinstalled in reverse order of removal
2. Verify all electrical connectors are fully seated with locking tabs engaged
3. Double-check that all fasteners are torqued to specification using calibrated torque wrench
4. Ensure no tools or parts are left in drive unit area before closing covers
5. Verify wiring harness has proper routing with no pinch points

Verification

• Start vehicle and verify no warning lights illuminate on dashboard
• Use scan tool to verify knock sensor is providing signal to drive unit controller
• Monitor knock sensor data in real-time using diagnostic scanner - should show stable readings at idle
• Perform test drive and monitor for any vibration-related fault codes
• Check all reinstalled panels and covers for secure fit with no rattles
• Inspect ground under vehicle after 24 hours for any signs of fluid leakage from gasket areas
• Verify knock sensor readings are within normal parameters during acceleration and deceleration

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