This procedure covers the removal and replacement of the coolant temperature sensor on the 2022 Rivian EDV 500's electric drive unit cooling system.

Warnings

Tools required

Parts

• Coolant temperature sensor × 1 — Use OEM Rivian specification
• O-ring seal for coolant sensor × 1 — Usually included with sensor
• Coolant hose clamps (if damaged) × 2 — Use OEM specification

Fluids

• EV Battery/Motor Coolant — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Ensure vehicle has been off and cooling for minimum 2 hours
3. Open hood and locate the 12V battery disconnect switch in the frunk
4. Disconnect 12V battery using the service disconnect and wait 10 minutes
5. Verify high-voltage system is de-energized (no indicator lights on dash when attempting to power on)
6. Locate the coolant temperature sensor on the front drive unit coolant manifold (driver side of front motor assembly)
7. Place coolant drain pan beneath vehicle under front drive unit area

Procedure

1. 1

   Access the coolant temperature sensor
   Remove the front underbody panel fasteners and lower the protective panel to access the front drive unit. The coolant temperature sensor is mounted on the coolant outlet manifold on the driver side of the front motor assembly. Remove any wire loom clips securing the sensor harness to nearby components.
2. 2

   Relieve cooling system pressure
   Locate the coolant reservoir in the frunk area. Slowly turn the reservoir cap counter-clockwise to the first detent and allow pressure to escape. Wait 30 seconds, then remove the cap completely. This prevents coolant from spraying when the sensor is removed.
3. 3

   Drain coolant from system
   Locate the coolant drain valve on the bottom of the front drive unit cooling circuit. Attach a suitable hose to direct coolant into the drain pan. Open the drain valve and allow approximately 3-4 quarts to drain until the coolant level is below the sensor location. Close the drain valve when complete.
4. 4

   Disconnect sensor electrical connector
   Press the locking tab on the coolant temperature sensor electrical connector and pull straight away from the sensor. Do not pull on the wires. Inspect the connector pins for corrosion or damage. Clean with electrical contact cleaner if necessary.
5. 5

   Test old sensor (optional diagnostic step)
   If diagnosing a faulty sensor, use a digital multimeter set to resistance mode to measure across the sensor terminals. At room temperature (68°F), resistance should be approximately 2,000-3,000 ohms. If the reading is infinite (open circuit) or near zero (short circuit), the sensor has failed.
6. 6

   Remove coolant temperature sensor
   Using an appropriate deep socket (typically 19mm or 22mm depending on sensor design), carefully unscrew the coolant temperature sensor from the coolant manifold. Turn counter-clockwise. Some residual coolant will drain when the sensor is removed. Remove the sensor completely and inspect the threads and O-ring sealing surface.
7. 7

   Clean sensor mounting bore
   Use a clean, lint-free cloth to wipe the sensor mounting bore in the coolant manifold. Remove any old O-ring material or debris. Use a non-metallic wire brush if necessary to clean the threads. Ensure no contamination enters the coolant system.
8. 8

   Prepare new sensor
   Remove the new coolant temperature sensor from packaging. Verify it matches the original sensor design. Check that the new O-ring seal is properly seated in the sensor groove. Apply a thin film of fresh EV coolant to the O-ring to aid installation and create a proper seal.
9. 9

   Install new coolant temperature sensor
   Thread the new sensor into the coolant manifold by hand, turning clockwise. Ensure it threads smoothly without cross-threading. Once hand-tight, use a torque wrench and appropriate socket to tighten the sensor. Since no specific torque value is provided in the database, follow the torque specification on the sensor packaging or tighten to snug plus 1/4 turn (typically 15-20 ft-lbs for this type of sensor).
10. 10

    Reconnect electrical connector
    Align the electrical connector with the sensor terminals and push firmly until the locking tab clicks into place. Tug gently on the connector to verify it is fully seated and locked. Reattach any wire loom clips to secure the harness.
11. 11

    Refill cooling system
    Fill the coolant reservoir with fresh EV Battery/Motor Coolant to the COLD FILL line marked on the reservoir. Add coolant slowly to prevent air pockets. Use approximately 2 quarts or as needed to reach proper level. Do not overfill.
12. 12

    Bleed air from cooling system
    With the coolant reservoir cap removed, reconnect the 12V battery temporarily. Power on the vehicle to Ready mode without driving. Allow the coolant pumps to circulate coolant for 2-3 minutes. Monitor the coolant level in the reservoir and add coolant as the level drops due to air purging. Repeat until level stabilizes.
13. 13

    Check for leaks
    With the vehicle still in Ready mode and coolant circulating, carefully inspect the new coolant temperature sensor for any signs of coolant leakage around the threads or O-ring seal. Also check the drain valve is fully closed and not leaking. If any leaks are detected, power off the vehicle and re-tighten as necessary.
14. 14

    Verify sensor operation
    Using the Rivian diagnostic scanner or OBD2 tool, connect to the vehicle and navigate to live data for the cooling system. Verify the coolant temperature sensor is providing a reasonable temperature reading (should be close to ambient temperature if system was fully cooled). Check for any diagnostic trouble codes related to the coolant temperature sensor.
15. 15

    Reinstall underbody panels and finalize
    Power off the vehicle and disconnect the 12V battery again. Reinstall the front underbody protective panel and secure all fasteners. Remove the drain pan from under the vehicle. Reconnect the 12V battery permanently. Install the coolant reservoir cap and close the hood.

Reassembly

1. Ensure all coolant system connections are tight and leak-free
2. Verify underbody panels are properly secured to protect drive unit components
3. Confirm coolant level is at COLD FILL line on reservoir
4. Double-check that 12V battery is reconnected and secured

Verification

• Start the vehicle and allow it to run in Ready mode for 5 minutes while monitoring coolant temperature readings on the diagnostic scanner
• Verify coolant temperature rises gradually and smoothly as the system operates, indicating proper sensor function
• Check that no diagnostic trouble codes are present related to coolant temperature sensor circuit
• Perform a final visual inspection under the vehicle for any coolant leaks around the sensor or drain valve
• Test drive the vehicle and monitor for any coolant temperature warnings or anomalies on the dashboard
• After test drive, recheck coolant level when system is cool and top off if necessary to HOT FILL line

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