This procedure covers the replacement of the coolant temperature sensor on the 2023 Rivian EDV 500's electric motor cooling system, including coolant draining and system refilling.

Warnings

Tools required

Parts

• Coolant temperature sensor × 1 — Use OEM Rivian specification
• Coolant temperature sensor O-ring or gasket × 1 — Use OEM Rivian specification
• EV Battery/Motor Coolant × 2 — Rivian OEM EV coolant

Fluids

• EV Battery/Motor Coolant — 2 qt

Preparation

1. Ensure vehicle has been off and cooling for minimum 2 hours
2. Park vehicle on level surface and engage parking brake
3. Access the Rivian service mode through the center display: Settings > Service > Service Mode
4. Perform high voltage disconnect procedure: open front hood, locate HV service disconnect under storage compartment, remove cover and disconnect HV connector
5. Wait 5 minutes after HV disconnect for capacitor discharge
6. Raise vehicle and secure on jack stands at manufacturer lift points
7. Remove underbody protective panels to access motor cooling system (front motor for AWD configuration)
8. Place drain pan beneath front motor area
9. Have diagnostic scanner ready to clear fault codes after repair

Procedure

1. 1

   Drain motor cooling system
   Locate the coolant drain valve on the front motor cooling circuit (driver side of motor housing). Slowly open the drain valve to release system pressure gradually, then fully open to drain coolant into the collection pan. Drain approximately 3-4 quarts or until coolant flow stops from the drain point.
2. 2

   Locate coolant temperature sensor
   The coolant temperature sensor is mounted on the front motor housing, typically on the coolant outlet manifold near the upper motor mount. It will have a two-pin electrical connector and thread directly into the aluminum housing. Remove any heat shielding or wire routing clips that obstruct access.
3. 3

   Disconnect sensor electrical connector
   Press the locking tab on the coolant temperature sensor connector and carefully pull the connector straight back from the sensor. Do not pull on the wires. Inspect connector pins for corrosion or damage and clean if necessary.
4. 4

   Remove old coolant temperature sensor
   Using an appropriately sized deep socket or wrench (typically 19mm or 22mm), carefully unthread the coolant temperature sensor from the motor housing. Expect residual coolant to drain from the sensor port. Keep rags ready to catch spillage. Inspect the sensor threads and housing threads for damage or debris.
5. 5

   Clean sensor mounting location
   Use a wire brush to carefully clean the threaded sensor port in the motor housing, removing any old sealant, corrosion, or debris. Wipe clean with a lint-free rag. Inspect threads for damage. If threads are damaged, stop and consult Rivian service documentation for thread repair procedures.
6. 6

   Prepare new sensor
   Remove new coolant temperature sensor from packaging. Verify correct part number matches Rivian specification. Install new O-ring or gasket onto sensor if supplied separately. Some sensors come with factory-applied thread sealant; if yours does not, apply a thin coat of approved high-temperature coolant-compatible thread sealant to the threads (typically 2-3 threads from the tip).
7. 7

   Install new coolant temperature sensor
   Thread the new sensor into the motor housing by hand initially to ensure proper thread engagement and prevent cross-threading. Once hand-tight, use a torque wrench to tighten the sensor. Since no manufacturer torque specification is provided in the database, tighten to typical EV coolant sensor specification of 15-20 ft-lbs (20-27 Nm), or follow any torque specification marked on the sensor packaging.
8. 8

   Reconnect electrical connector
   Align the electrical connector with the sensor terminals and push firmly until the locking tab clicks into place. Gently tug on the connector to verify it is fully seated and locked. Reinstall any wire routing clips or heat shielding removed earlier.
9. 9

   Close coolant drain valve
   Ensure the coolant drain valve is fully closed and tightened. Wipe away any spilled coolant from the motor housing and surrounding components.
10. 10

    Refill cooling system
    Locate the coolant reservoir fill point (typically in the front compartment near the motor). Using a funnel, slowly add Rivian-specified EV Battery/Motor Coolant. Fill to the MAX or FULL COLD mark on the reservoir. Add approximately 2 quarts initially, then proceed to bleeding process. Do not overfill.
11. 11

    Bleed cooling system
    With the vehicle still in service mode, use the Rivian diagnostic scanner to activate the coolant pump purge cycle. This will circulate coolant and purge air from the system. Run the purge cycle for 5-10 minutes while monitoring coolant level in the reservoir. Add coolant as needed to maintain proper level. If no diagnostic tool is available, reconnect HV system and activate drive mode briefly to circulate coolant, then recheck level (ensure proper safety precautions before energizing HV system).
12. 12

    Check for leaks
    With the cooling system pressurized (pump running or vehicle activated), carefully inspect the coolant temperature sensor installation point for any signs of leakage. Check the sensor threads, O-ring seal, and surrounding connections. Also inspect the drain valve. If any leaks are detected, depressurize system, verify sensor installation, and check O-ring condition.
13. 13

    Clear diagnostic codes and verify sensor function
    Using the Rivian diagnostic scanner, clear any coolant temperature sensor fault codes that may have been set. Start the vehicle and monitor the coolant temperature reading on the diagnostic scanner. Verify the sensor provides a realistic reading (typically 60-90°F when cold). Allow the vehicle to run through a thermal management cycle and confirm temperature readings respond appropriately.

Reassembly

1. Reinstall all underbody protective panels removed during access
2. Lower vehicle from jack stands
3. Verify coolant level one final time with vehicle on level ground and add coolant if needed to reach FULL COLD mark
4. Exit service mode through center display menu
5. Reconnect high voltage service disconnect if it was left disconnected
6. Close and secure front hood and any opened compartments

Verification

• Start vehicle and verify no coolant temperature warning messages appear on the instrument cluster
• Using diagnostic scanner, confirm coolant temperature sensor provides active readings within expected range
• Test drive vehicle for 15-20 minutes and monitor thermal management system operation
• After test drive, recheck coolant level when system is cool and top off if necessary
• Inspect sensor installation area for any signs of coolant leakage
• Verify no fault codes are present in the vehicle diagnostic system

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