Coolant Temperature Sensor

Replace the coolant temperature sensor (CTS) on the 1992 Dodge Viper 8.0L V10 engine to restore accurate temperature readings to the ECM and gauge cluster.

Warnings

Tools required

Parts

• Coolant temperature sensor × 1 — Use OEM specification

Fluids

• Ethylene glycol 50/50 — 2 qt

Preparation

1. Ensure engine is completely cold to the touch (wait minimum 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Disconnect negative battery cable to prevent false codes during sensor disconnection
4. Locate coolant temperature sensor on driver side of intake manifold near front of engine, below throttle body area

Procedure

1. 1

   Drain coolant to below sensor level
   Place drain pan under radiator. Open radiator petcock at bottom of radiator driver side to drain coolant until level drops below the sensor location on the intake manifold. Monitor coolant level in overflow tank; when it stops dropping, sufficient coolant has drained. Close petcock when complete.
   Torque spec

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

   Disconnect sensor electrical connector
   Locate the electrical connector on top of the coolant temperature sensor (typically a two-wire connector for the ECM sensor). Press the release tab on the connector and pull straight up to disconnect. Residual coolant may drip from the sensor area; have shop towels ready.
3. 3

   Remove coolant temperature sensor
   Using an appropriately sized deep socket or wrench (verify sensor hex size), turn the sensor counterclockwise to remove. The sensor will thread out of the intake manifold boss. Expect a small amount of coolant (approximately 1/2 cup) to drain from the sensor port. Have shop towels or drain pan positioned to catch spillage.
4. 4

   Inspect and clean sensor port
   Inspect the intake manifold threads for damage or corrosion. Use a wire brush to clean any old sealant or debris from the threads in the manifold port. Wipe the area clean with a shop towel. Verify threads are intact and not stripped.
5. 5

   Prepare new sensor for installation
   If the new sensor is not pre-coated with sealant, apply a light coating of the manufacturer-recommended coolant-safe thread sealant to the threads of the new coolant temperature sensor (avoid Teflon-type sealants that can insulate the sensor if a ground path is required). Apply sealant only to the first 2-3 threads; do not allow sealant to contaminate the sensor tip. Avoid excess sealant that could enter the cooling system.
6. 6

   Install new coolant temperature sensor
   Thread the new sensor into the intake manifold port by hand, turning clockwise. Ensure the sensor threads in smoothly without resistance. Once hand-tight, use the 19mm socket to tighten the sensor an additional 1/4 to 1/2 turn past hand-tight. Do NOT use excessive force; the sensor should seat firmly but not require heavy torque. Tapered pipe threads seal through compression, not torque.
7. 7

   Reconnect electrical connector
   Push the electrical connector onto the new sensor terminal until it clicks into place. Tug gently on the connector to verify it is fully seated and locked.
8. 8

   Refill cooling system
   Add ethylene glycol 50/50 coolant mixture to the radiator and overflow tank to restore proper level. Fill radiator to neck and overflow tank to FULL COLD mark. Reinstall radiator cap. Start engine and allow to warm to operating temperature while monitoring for leaks at sensor location.
9. 9

   Bleed air and verify operation
   With engine at operating temperature, check coolant level again and top off as necessary. Air pockets will purge through normal operation. Verify temperature gauge reads normally (approximately 195-210°F operating range). Check for leaks around sensor base; any seepage indicates insufficient thread seal or cross-threading.
10. 10

    Reconnect battery and clear codes
    Reconnect negative battery cable. Start engine and verify normal operation. This vehicle predates OBD-II; if a fault indication is present, retrieve any stored codes using the Chrysler key-cycle (on-off-on) method to read flashes from the instrument cluster, then clear codes by disconnecting the battery. Test drive vehicle to confirm normal temperature operation.

Reassembly

1. Reinstall components in reverse order of removal
2. Verify all electrical connections are secure and locked
3. Double-check coolant level after first heat cycle

Verification

• Engine temperature gauge reads normal operating range (center position) after warm-up
• No coolant leaks visible at sensor base after heat cycle
• No check engine light or temperature-related diagnostic codes present
• Cooling fans cycle on and off at appropriate temperatures during extended idle

Related trouble codes on this vehicle

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

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