O2 Sensor - Downstream

This procedure covers the removal and replacement of the downstream oxygen sensor(s) on a 2015-2020 Ford F-150 with the 5.0L Coyote V8 engine.

Warnings

Tools required

Parts

• Downstream O2 sensor (Bank 1 and/or Bank 2) × 1 — Motorcraft DY-1435 or equivalent

Preparation

1. Park vehicle on level surface and apply parking brake
2. Chock the front wheels securely
3. Allow exhaust system to cool completely (minimum 2 hours after last operation)
4. Raise and safely support the vehicle on jack stands or a lift to access the underside
5. Locate the downstream O2 sensor(s) positioned after the catalytic converter(s) in the exhaust pipe

Procedure

1. 1

   Disconnect sensor electrical connector
   Trace the O2 sensor wire harness from the sensor up to the electrical connector. Press the release tab and disconnect the electrical connector. The connector may be clipped to a bracket; unclip if necessary to provide access.
2. 2

   Inspect sensor and exhaust threads
   Visually inspect the sensor for any visible damage, corrosion, or carbon buildup. Check the exhaust bung threads for damage or excessive rust. If the sensor appears severely corroded or seized, apply penetrating oil to the threads and allow 15-30 minutes to soak before removal.
3. 3

   Remove the downstream O2 sensor
   Using the O2 sensor socket and ratchet with extension, loosen the sensor by turning counterclockwise. The sensor requires approximately 33 lb-ft to install, so expect moderate resistance during removal. If the sensor is seized, use a breaker bar for additional leverage. Once loosened, unthread the sensor by hand and remove it from the exhaust pipe.
   ⚠Avoid using excessive force that could damage the exhaust bung threads. If sensor will not budge after penetrating oil treatment, heating the area with a torch may be necessary.
4. 4

   Clean exhaust bung threads
   Use a wire brush to clean the threads inside the exhaust bung where the sensor mounts. Remove any carbon deposits, rust, or old anti-seize compound. Ensure threads are clean and undamaged to ensure proper seating of the new sensor.
5. 5

   Prepare new O2 sensor
   Remove the new O2 sensor from its packaging. Apply a thin coat of anti-seize compound to the threads of the new sensor only. Do not allow anti-seize to contact the sensor tip or the perforated protective sleeve, as this will contaminate the sensor element and cause premature failure.
   Torque spec

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

   Install new O2 sensor
   Thread the new O2 sensor into the exhaust bung by hand, ensuring it threads smoothly without cross-threading. Once hand-tight, use the O2 sensor socket and torque wrench to tighten to specification at 45 Nm (33 lb-ft). Ensure the sensor wire routing will not contact hot exhaust components or moving parts.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
7. 7

   Reconnect electrical connector
   Route the O2 sensor wire harness to avoid contact with the exhaust system, driveshaft, or suspension components. Connect the electrical connector to the vehicle harness until it clicks securely. If applicable, secure the connector to its mounting clip or bracket.

Reassembly

1. Verify sensor wire routing does not interfere with any moving or hot components
2. Lower the vehicle carefully from jack stands or lift
3. Remove wheel chocks

Verification

• Start the engine and verify no exhaust leaks are present at the O2 sensor location
• Allow the engine to reach operating temperature and confirm the check engine light does not illuminate
• Use an OBD-II scanner to verify the new O2 sensor is reading properly and no diagnostic trouble codes are present
• Perform a test drive and confirm engine runs smoothly with no hesitation or rough idle conditions

Related trouble codes on this vehicle

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