Complete replacement of all oxygen sensors on the 2014 Ram 2500 with 6.7L Cummins Diesel engine, including both upstream and downstream sensors in the exhaust system.

Warnings

Tools required

Parts

• Upstream O2 sensor (NOx sensor) × 1 — Mopar 68233296AA or equivalent
• Downstream O2 sensor (post-DPF) × 1 — Mopar 68157596AA or equivalent

Preparation

1. Ensure engine and exhaust system are completely cool to the touch
2. Park vehicle on level surface and engage parking brake
3. Place wheel chocks behind rear wheels
4. Disconnect negative battery cable to prevent false codes during sensor replacement
5. Raise front of vehicle with floor jack and support securely on jack stands rated for vehicle weight
6. Remove any heat shields or skid plates blocking access to exhaust system
7. Spray all O2 sensor threads with penetrating oil and allow 15-20 minutes to soak

Procedure

1. 1

   Locate all O2 sensors
   The 6.7L Cummins diesel uses two O2 sensors: one upstream NOx sensor located before the DPF (Diesel Particulate Filter) on the exhaust downpipe, and one downstream O2 sensor located after the DPF in the mid-exhaust section. Identify both sensor locations and verify electrical connector access before proceeding.
2. 2

   Disconnect upstream NOx sensor electrical connector
   Locate the upstream NOx sensor electrical connector near the left side of the engine bay. Press the red safety tab and slide it out, then depress the connector lock tab while pulling the connector straight off the sensor. Do not pull on wires. Inspect connector and pins for corrosion or damage.
3. 3

   Remove upstream NOx sensor
   Using the O2 sensor socket and ratchet with extension, carefully loosen the upstream NOx sensor. These sensors can be tight due to heat cycling. If sensor is seized, apply additional penetrating oil and allow to soak, or use a breaker bar for additional leverage. Turn counterclockwise to remove. Once loose, unthread sensor by hand and remove from exhaust pipe.
4. 4

   Clean upstream sensor bung threads
   Use a wire brush to thoroughly clean the threads in the exhaust pipe where the sensor was installed. Remove all carbon buildup, rust, and old anti-seize compound. Clean threads will ensure accurate torque values and proper sensor sealing.
5. 5

   Install new upstream NOx sensor
   Apply a thin coat of nickel-based anti-seize compound to the threads of the new upstream NOx sensor only - do not get any on the sensor element or tip. Thread sensor into exhaust bung by hand until finger-tight to prevent cross-threading. Using O2 sensor socket and torque wrench, tighten to specification.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
6. 6

   Reconnect upstream NOx sensor connector
   Route sensor wire to avoid contact with hot exhaust components or moving parts. Plug electrical connector onto sensor until it clicks into place. Slide red safety tab back into locked position. Gently tug on connector to verify it is fully seated.
7. 7

   Disconnect downstream O2 sensor electrical connector
   Locate the downstream O2 sensor connector, typically secured to the frame rail or body near the mid-exhaust section. Press connector release tab and disconnect. The connector may be secured with a clip or zip tie that must be removed first.
8. 8

   Remove downstream O2 sensor
   Access the downstream O2 sensor from underneath the vehicle. It is located in the exhaust pipe after the DPF canister. Using O2 sensor socket and ratchet, loosen and remove the sensor by turning counterclockwise. If sensor is difficult to remove, apply heat with a heat gun (not torch) to help break corrosion bond.
9. 9

   Clean downstream sensor bung threads
   Thoroughly clean the threads in the downstream exhaust pipe using a wire brush. Remove all carbon deposits and old anti-seize. Ensure threads are clean and undamaged to allow proper seating of new sensor.
10. 10

    Install new downstream O2 sensor
    Apply thin coat of nickel-based anti-seize to threads of new downstream O2 sensor only - keep sensor element clean. Hand-thread sensor into exhaust bung until snug, then torque to specification using O2 sensor socket and torque wrench.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
11. 11

    Reconnect downstream O2 sensor connector
    Route sensor wire to prevent contact with exhaust, driveshaft, or suspension components. Connect electrical connector until it clicks, then secure with any original clips or new zip ties. Ensure adequate slack for suspension movement.
12. 12

    Reinstall heat shields and skid plates
    Reinstall any heat shields or skid plates that were removed for access. Ensure all mounting hardware is tight and shields are properly positioned to prevent contact with exhaust components.
    Torque spec

    Heat Shield Bolts10 Nm (7 lb-ft)

    Mounting Bolts37 Nm (27 lb-ft)

Reassembly

1. Lower vehicle from jack stands carefully
2. Reconnect negative battery cable
3. Double-check that all electrical connectors are fully seated and locked
4. Verify no tools or parts were left in engine bay or under vehicle

Verification

• Start engine and allow to idle - listen for any exhaust leaks at sensor locations
• Check for any exhaust smoke or hissing sounds indicating improper sensor seating
• Use scan tool to verify O2 sensor signals are being received by ECM (voltages should fluctuate)
• Clear any diagnostic trouble codes with scan tool
• Perform test drive of at least 15 minutes to allow sensors to reach operating temperature
• Re-scan for codes after test drive - no O2 sensor codes should be present
• Verify check engine light is off after completing drive cycle

More procedures for this vehicle