exhaust

O2 Sensor - Downstream

for 2014 Ram 2500 6.7L I6 Cummins Diesel · 4WD

Difficulty

Easy

Time

48 min

Tools

Steps

This procedure covers the removal and replacement of the downstream oxygen sensor on the 2014 Ram 2500 with 6.7L Cummins diesel engine.

Warnings

⚠️Allow exhaust system to cool completely before beginning work. Exhaust components can remain hot for over an hour after engine shutdown and cause severe burns.

⚠Do not apply anti-seize to sensor tip or any part other than threads. Contamination of the sensor element will cause immediate failure.

⚠Oxygen sensors can be difficult to remove when seized. Excessive force may damage exhaust components or break the sensor off in the bung, requiring welding or pipe replacement.

ℹ️The downstream O2 sensor on the 6.7L Cummins is located after the diesel particulate filter (DPF) in the exhaust system.

Tools required

Oxygen sensor socket (7/8" or 22mm)Essential

3/8" drive ratchet with extensionEssential

Wire brush

Anti-seize compoundEssential

Jack and jack standsEssential

Wheel chocksEssential

Torque wrenchEssential

Penetrating oil

Wire cutters (if sensor is seized)

Parts

Downstream oxygen sensor × 1 — Use OEM Mopar sensor or equivalent meeting OE specifications
Anti-seize compound × 1 — High temperature nickel-based anti-seize

Preparation

Park vehicle on level ground and apply parking brake
Place wheel chocks behind rear wheels
Allow exhaust system to cool completely (minimum 1 hour after engine operation)
Raise vehicle using jack and support securely on jack stands at frame rails
Locate downstream oxygen sensor in exhaust pipe after the DPF assembly on driver side of vehicle

Procedure

1
Disconnect oxygen sensor electrical connector
Follow the oxygen sensor wiring harness upward from the sensor to locate the electrical connector. Press the release tab and carefully disconnect the connector. Ensure no dirt or debris enters the connector.
2
Free the wiring harness
Locate any clips or brackets securing the oxygen sensor wiring to the vehicle or exhaust system. Remove or release these clips to provide slack for sensor removal. Note routing for reinstallation.
3
Apply penetrating oil if necessary
If the sensor has been in service for an extended period, spray penetrating oil around the sensor base where it threads into the exhaust pipe. Allow 10-15 minutes to penetrate before attempting removal. This step is optional for newer sensors.
4
Remove the downstream oxygen sensor
Using the oxygen sensor socket and ratchet with extension, carefully loosen the sensor in a counterclockwise direction. Once broken free, unscrew the sensor by hand if possible. If sensor is seized and will not break free with reasonable force, consider heating the bung with a torch (ensuring wiring is protected) or as a last resort, cut the wiring and use a standard 7/8" wrench for additional leverage.
5
Inspect and clean the exhaust bung
Once the old sensor is removed, inspect the threaded bung in the exhaust pipe for damage or excessive carbon buildup. Use a wire brush to clean the threads thoroughly. Check that threads are not stripped or cross-threaded.
6
Prepare the new oxygen sensor
Remove the new oxygen sensor from its protective packaging. Apply a thin, even coat of high-temperature nickel-based anti-seize compound to the sensor threads only. Do NOT allow anti-seize to contact the sensor tip or element. Use sparingly to avoid excess compound being pushed into the exhaust stream.
7
Install the new oxygen sensor
Carefully thread the new sensor into the exhaust bung by hand, ensuring it starts straight and does not cross-thread. Thread in until hand-tight, then use the oxygen sensor socket and torque wrench to tighten to specification.
Torque spec
O2 Sensor45 Nm (33 lb-ft)
8
Reconnect electrical connector and secure wiring
Route the oxygen sensor wiring following the original path noted during disassembly. Ensure wiring is not in contact with hot exhaust components or sharp edges. Connect the electrical connector firmly until the locking tab clicks into place. Reinstall any wiring clips or brackets.
9
Lower vehicle and clear diagnostic codes
Remove jack stands and lower vehicle to the ground. Using an OBD-II scan tool, clear any stored oxygen sensor or emissions-related diagnostic trouble codes from the engine control module. This ensures proper monitoring of the new sensor.

Reassembly

Ensure all wiring clips and brackets are properly secured
Verify oxygen sensor electrical connector is fully seated and locked
Confirm no tools or parts were left in the work area under the vehicle

Verification

Start the engine and allow it to reach operating temperature while monitoring for exhaust leaks around the sensor
Check that no oxygen sensor or emissions-related warning lights are illuminated on the instrument cluster
Using a scan tool, verify the downstream oxygen sensor is providing live data readings to the ECM
Perform a test drive and confirm no check engine light illuminates
Re-scan for codes after test drive to ensure no new faults are present