Coolant Temperature Sensor

Replace the coolant temperature sensor on a 2005 Dodge Viper 8.3L V10, including partial coolant drain, sensor removal, installation with sealant, and system refill.

Warnings

Tools required

Parts

• Coolant temperature sensor × 1 — Use OEM specification (Mopar 5269870AA or equivalent)
• Thread sealant with PTFE (pipe thread sealant) × 1 — Use OEM specification

Fluids

• Zerex G-05 HOAT 50/50 — 2 qt

Preparation

1. Ensure engine is completely cold to the touch (minimum 2 hours after last operation).
2. Park vehicle on level ground and engage parking brake.
3. Place drain pan under radiator drain petcock.
4. Open hood and locate coolant temperature sensor on driver side of engine near front of cylinder head.

Procedure

1. 1

   Drain Partial Coolant
   Open the radiator drain petcock at the bottom of the radiator to drain approximately 2 quarts of coolant into the drain pan. The coolant level only needs to drop below the sensor mounting location. Close the petcock once coolant level is below the sensor.
   Torque spec

   Drain Petcock7 Nm (5 lb-ft)
2. 2

   Disconnect Battery Negative Terminal
   Disconnect the negative battery terminal to prevent potential short circuits and clear any stored sensor codes. Use a 10mm wrench or socket to loosen the terminal clamp nut and move the cable away from the battery post.
   ℹ️Wait at least 2 minutes after disconnecting battery before proceeding to allow capacitors to discharge.
3. 3

   Disconnect Sensor Electrical Connector
   Locate the electrical connector on the coolant temperature sensor. Press the release tab on the connector and pull straight away from the sensor body. Do not pull on the wires themselves. Clean any coolant residue from the connector with a shop towel.
   ⚠The connector release tab may be brittle on this 2005 model. Apply gentle pressure only to avoid breaking the tab.
4. 4

   Remove Coolant Temperature Sensor
   Using the correct deep socket or open-end wrench for the sensor hex (verify size — commonly around 19mm, but confirm on the actual sensor), carefully unthread the coolant temperature sensor from its mounting location. Turn counterclockwise to remove. Expect a small amount of residual coolant to drain when the sensor is removed. Have a shop towel ready to catch drips.
   ℹ️If sensor is seized, apply gentle heat with a heat gun (not torch) to the surrounding area for 30-60 seconds to help break the seal.
5. 5

   Inspect Mounting Threads
   Inspect the threads in the engine block or thermostat housing where the sensor was mounted. Look for debris, corrosion, or damage. Clean threads with a shop towel if minor contamination is present. If threads are damaged or cross-threaded, the housing may require professional repair or replacement before proceeding.
   ⚠Do not use wire brushes or thread chasers on aluminum threads without proper training, as this can cause more damage than it repairs.
6. 6

   Prepare New Sensor
   If the sensor uses a tapered pipe thread, apply a thin coat of pipe thread sealant with PTFE to the threads of the new coolant temperature sensor. If the sensor seals with an integral O-ring or gasket, do NOT apply thread sealant. Do not apply sealant to the first 1-2 threads closest to the sensor tip, and keep sealant away from the sensor element itself. Use only thread sealant rated for coolant system use.
   ⚠Excess thread sealant can contaminate the coolant system or interfere with sensor operation. Apply sparingly.
7. 7

   Install New Sensor
   Thread the new coolant temperature sensor into the mounting location by hand, turning clockwise. Ensure the sensor threads smoothly without resistance for at least 3-4 full turns. Once hand-tight, use the deep socket and torque wrench to tighten the sensor to the manufacturer's specification. For the Viper 8.3L V10, tighten to the factory service manual specification (verify exact value; coolant temperature sensors in aluminum are commonly in the 7-15 lb-ft range — do not exceed manual spec).
   ⚠️Stop immediately if you feel binding or cross-threading. Back out the sensor, inspect threads, and restart. Forcing a cross-threaded sensor will destroy the aluminum threads.
8. 8

   Reconnect Electrical Connector
   Push the electrical connector firmly onto the new coolant temperature sensor until you hear or feel a distinct click. Gently tug on the connector to verify it is fully seated and locked in place.
   ℹ️Ensure the connector seal is properly aligned to prevent moisture intrusion.
9. 9

   Refill Coolant System
   Using a funnel, add Zerex G-05 HOAT 50/50 coolant through the radiator cap opening (not the overflow reservoir) until the level reaches the bottom of the filler neck. Add approximately 2 quarts to replace what was drained. Allow coolant to settle for 1-2 minutes and top off as needed. Note: The 8.3L V10 cooling system holds a large total volume (verify exact capacity in the service manual). You are only replacing the small amount drained during sensor removal.
   ℹ️The 8.3L V10 system holds 19 quarts total. You are only replacing the small amount drained during sensor removal.
10. 10

    Bleed Air from Cooling System
    With the radiator cap still off, start the engine and allow it to idle. Run the engine until the thermostat opens (coolant temperature reaches approximately 195°F, typically 5-10 minutes). Watch for coolant circulation in the radiator. Add coolant as the level drops due to air purging from the system. Rev engine to 2000 RPM 2-3 times to help purge trapped air.
    ⚠️Monitor engine temperature closely during bleeding. If temperature exceeds normal operating range, shut off engine immediately and allow to cool.
    ⚠Keep hands and tools away from moving belts and fans during this step.
11. 11

    Final Coolant Level and Cap Installation
    Once thermostat has opened and air is purged, top off coolant to the bottom of the radiator filler neck. Install the radiator cap by pressing down and turning clockwise until it locks. Check the overflow reservoir and fill to the COLD mark with 50/50 coolant if low.
    ℹ️The system may require additional topping off after the next cold cycle as residual air escapes.
12. 12

    Reconnect Battery and Clear Codes
    Reconnect the negative battery terminal and tighten the clamp nut to secure. Start the engine and verify that no check engine light is illuminated. If the check engine light remains on, use an OBD-II scanner to verify no coolant temperature sensor codes are present and clear any stored codes.
    ℹ️Some residual codes may remain stored even after repair. Clearing codes allows you to verify the new sensor is functioning correctly.

Reassembly

1. No disassembly of additional components was required for this procedure.

Verification

• Start engine and allow to reach normal operating temperature. Verify temperature gauge reads in normal range (approximately 195-210°F).
• Check for coolant leaks around the new sensor location with engine running and at operating temperature.
• Use an OBD-II scanner to verify coolant temperature sensor is reporting reasonable values (should match actual engine temperature within 10-15°F).
• Verify no check engine light is illuminated and no coolant temperature sensor diagnostic codes are present.
• Check coolant level in overflow reservoir after engine cools. Top off to COLD mark if necessary.
• Test drive vehicle and monitor temperature gauge for normal operation under varying load conditions.

Related trouble codes on this vehicle

Codes that commonly send this job to the bay — tap one for symptoms, causes, and diagnostic steps.

Chasing one of these codes and not sure which part is guilty? Ask a master mechanic about YOUR car →

More procedures for this vehicle