Replace the coolant temperature sensor on the 6.7L Cummins diesel engine to restore proper engine temperature monitoring and ECM function.

Warnings

Tools required

Parts

• Coolant temperature sensor × 1 — Mopar 05149062AA or equivalent
• Coolant temperature sensor O-ring × 1 — Usually included with sensor

Fluids

• Mopar OAT Coolant (Purple) — 2 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Open hood and locate coolant temperature sensor on the thermostat housing (driver side of engine)
4. Place drain pan under work area to catch coolant spillage
5. Have replacement sensor and coolant ready before starting

Procedure

1. 1

   Relieve cooling system pressure
   Slowly rotate the coolant reservoir cap counterclockwise to release any residual pressure. Remove cap completely and set aside. This prevents coolant from spraying when the sensor is removed.
2. 2

   Disconnect electrical connector
   Locate the coolant temperature sensor on the thermostat housing. Press the tab on the electrical connector and pull straight back to disconnect. Use a pick to release the tab if necessary. Move the harness aside to provide clearance.
3. 3

   Remove coolant temperature sensor
   Using a 19mm deep socket with extension, carefully loosen the coolant temperature sensor by turning counterclockwise. Once loose, unthread by hand and remove quickly to minimize coolant loss. Allow coolant to drain into pan. Note the orientation of the sensor for installation reference.
4. 4

   Inspect sensor bore and O-ring
   Examine the sensor bore in the thermostat housing for any debris, corrosion, or damage. Clean the sealing surface with a shop towel if necessary. Verify the new sensor includes a new O-ring and that it is properly seated in the sensor groove.
5. 5

   Install new coolant temperature sensor
   Thread the new coolant temperature sensor into the thermostat housing by hand to ensure proper thread engagement. Once hand-tight, use the 19mm deep socket and torque wrench to tighten to 9-12 Nm (7-9 lb-ft). Do not over-torque as the housing is aluminum and the sensor body can crack.
6. 6

   Reconnect electrical connector
   Push the electrical connector onto the new coolant temperature sensor until it clicks into place. Verify the locking tab is fully engaged by gently pulling on the connector.
7. 7

   Refill coolant system
   Using a funnel, slowly add Mopar OAT Purple coolant to the coolant reservoir until the level reaches the MAX cold fill line. Add coolant gradually to allow air to escape. Install the reservoir cap securely.
   Torque spec

   Bleed Screw9 Nm (7 lb-ft)
8. 8

   Bleed cooling system
   Start the engine and allow it to idle with the heater on maximum heat. Monitor coolant level in the reservoir and add coolant as needed as air purges from the system. Run engine until the thermostat opens and coolant begins circulating (approximately 10-15 minutes). If equipped, open the bleed screw on the thermostat housing to release trapped air, then close when coolant flows steadily.

Reassembly

1. Verify all electrical connections are secure and properly locked
2. Confirm coolant level is at the MAX cold fill line after engine has cooled
3. Wipe down any spilled coolant from engine bay components

Verification

• Start engine and verify no coolant leaks around the sensor installation point
• Using a scan tool, confirm the ECM is receiving proper coolant temperature readings (should rise from ambient to approximately 190-195°F at operating temperature)
• Verify the engine cooling fan cycles on and off normally as engine reaches operating temperature
• Check for proper heater operation inside the cab
• After first drive cycle, recheck coolant level when engine is cold and top off if necessary

More procedures for this vehicle