Replace the coolant temperature sensor on the Rivian EDV 500's electric motor cooling system to restore proper temperature monitoring and thermal management.

Warnings

Tools required

Parts

• Coolant temperature sensor × 1 — Use OEM Rivian specification
• Sensor O-ring or seal × 1 — Often included with sensor
• Coolant hose clamps (if damaged) × 2 — OEM size specific

Fluids

• EV Battery/Motor Coolant — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow cooling system to cool completely for minimum 2 hours
3. Raise vehicle on lift or secure with jack stands rated for vehicle weight
4. Remove front underbody panels to access motor cooling system components
5. Locate the 12V battery access panel behind front fascia and disconnect negative terminal
6. Wait 5 minutes for vehicle systems to fully power down
7. Connect scan tool and verify high-voltage system is deactivated
8. Place coolant drain pan under front motor area
9. Locate coolant temperature sensor on motor cooling circuit (typically mounted on coolant outlet housing)

Procedure

1. 1

   Drain cooling system
   Locate the cooling system drain valve on the motor coolant circuit. Carefully open the drain valve and allow coolant to drain into pan. You only need to drain enough coolant to drop the level below the sensor location, typically 1-2 quarts. Close drain valve when coolant level is below sensor mounting point.
2. 2

   Disconnect sensor electrical connector
   Locate the electrical connector on the coolant temperature sensor. Press the connector release tab and carefully pull the connector straight off the sensor. Do not pull on the wiring harness. Inspect connector terminals for corrosion or damage.
3. 3

   Remove coolant temperature sensor
   Using a 19mm deep socket, carefully unscrew the coolant temperature sensor from its mounting port in a counterclockwise direction. Be prepared for residual coolant spillage. Remove sensor completely and set aside. Inspect the sensor port threads for damage or debris.
4. 4

   Clean sensor mounting port
   Use clean shop towels to wipe the sensor mounting port threads and surrounding area. Remove any old thread sealant, coolant residue, or debris. Ensure the sealing surface is clean and free from damage. Inspect O-ring sealing surface for scratches or corrosion.
5. 5

   Prepare new sensor
   Remove new coolant temperature sensor from packaging. Verify the new sensor matches the original part. Install new O-ring or seal if provided separately. Apply a thin layer of coolant-safe thread sealant to the sensor threads, avoiding the first two threads and keeping sealant away from the sensor tip.
6. 6

   Install new sensor
   Thread the new coolant temperature sensor into the mounting port by hand, turning clockwise. Ensure sensor threads engage smoothly without cross-threading. Hand-tighten until sensor seats against the O-ring or sealing surface. Use torque wrench and 19mm socket to tighten to manufacturer specification (typically 15-25 ft-lb if spec becomes available). Do not overtighten as this may damage the sensor or port threads.
7. 7

   Reconnect electrical connector
   Push the electrical connector firmly onto the new coolant temperature sensor until you hear or feel a positive click. Gently tug on the connector to verify it is securely locked. Ensure the connector seal is properly seated to prevent moisture intrusion.
8. 8

   Refill cooling system
   Using the coolant refill funnel, add EV Battery/Motor Coolant to the system. Fill slowly to avoid air pockets. Add approximately 2 quarts or until coolant level reaches the appropriate fill line on the reservoir. Use only the specified EV coolant type to prevent damage to the cooling system.
9. 9

   Bleed cooling system
   Connect scan tool and access the cooling system service functions. Run the electronic coolant bleeding procedure through the Rivian diagnostic software. This will cycle the coolant pumps to purge air from the system. Monitor coolant level during bleeding and add coolant as needed. The process typically takes 10-15 minutes.
10. 10

    Verify sensor operation
    With scan tool connected, monitor the coolant temperature sensor reading. At ambient temperature, reading should be within normal range (typically 60-85°F depending on shop temperature). Verify reading is stable and not showing open circuit, short circuit, or implausible temperature codes.
11. 11

    Check for leaks
    Carefully inspect the sensor installation area for any signs of coolant leakage. Wipe the area dry with a clean towel, then observe for 2-3 minutes. Check that coolant is not seeping from the sensor threads or O-ring seal. Also inspect the drain valve for proper sealing.
12. 12

    Reconnect 12V battery and clear codes
    Reconnect the 12V battery negative terminal. Use scan tool to clear any diagnostic trouble codes related to the coolant temperature sensor. Verify no new codes are present. Exit diagnostic mode and allow vehicle to complete system initialization.

Reassembly

1. Reinstall front underbody panels and secure all fasteners
2. Lower vehicle from lift or jack stands
3. Verify coolant level in reservoir is at proper level when cold
4. Check that all tools and materials are removed from vehicle
5. Dispose of old coolant and sensor according to environmental regulations

Verification

• Start vehicle and allow cooling system to reach operating temperature while monitoring for leaks
• Use scan tool to verify coolant temperature sensor is reading accurately and tracking with expected temperature rise
• Verify no warning lights or messages appear on instrument cluster related to cooling system
• Check that thermal management system is operating normally with proper motor and battery cooling
• Perform a test drive and monitor coolant temperature readings remain within normal operating range (typically 140-180°F under normal conditions)
• Recheck coolant level after cool-down and top off if necessary
• Verify final coolant level is at the cold fill line on reservoir

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