This procedure covers the replacement of the downstream oxygen sensor(s) on the 2011-2014 Ford F-150 with the 5.0L V8 Coyote engine, located after the catalytic converters in the exhaust system.

Warnings

Tools required

Parts

• Downstream oxygen sensor (Bank 1) × 1 — Motorcraft DY-1355 or equivalent
• Downstream oxygen sensor (Bank 2) × 1 — Motorcraft DY-1355 or equivalent

Preparation

1. Ensure engine and exhaust system are completely cool to the touch
2. Park vehicle on level surface, engage parking brake, and place wheel chocks behind rear wheels
3. Raise and safely support the vehicle on jack stands at the frame rails
4. Locate the downstream oxygen sensors positioned after the catalytic converters on both exhaust banks
5. Spray penetrating oil on sensor threads if sensors have been in place for extended time, allow to soak 10-15 minutes

Procedure

1. 1

   Disconnect battery negative terminal
   Disconnect the negative battery cable to prevent stored diagnostic trouble codes from setting during sensor disconnection. Wait 2 minutes for powertrain control module to power down completely.
2. 2

   Access downstream oxygen sensor
   From underneath the vehicle, locate the downstream oxygen sensor on the bank being serviced. Bank 1 is the passenger side, Bank 2 is the driver side. The downstream sensor is located after the catalytic converter in the exhaust pipe, typically 18-24 inches behind the converter outlet.
3. 3

   Disconnect oxygen sensor electrical connector
   Trace the oxygen sensor wire to the electrical connector. Press the release tab and carefully pull the connector apart. If the connector is corroded or stuck, gently work it back and forth while pulling. Do not pull on the wires themselves.
4. 4

   Remove oxygen sensor wiring from retaining clips
   Follow the sensor wiring harness and release it from any retaining clips or brackets along the frame or exhaust system. This provides slack for sensor removal and prevents wire damage.
5. 5

   Remove downstream oxygen sensor
   Using the oxygen sensor socket and ratchet with extension, turn the sensor counterclockwise to remove. The sensor socket has a slot to allow clearance for the wiring pigtail. If the sensor is difficult to turn, apply additional penetrating oil and allow more soak time. Do not force as this may damage the exhaust bung threads.
   ⚠If sensor is seized and will not turn with reasonable force, heating the exhaust bung area with a torch may be necessary, but only after ensuring no fuel or flammable materials are nearby.
6. 6

   Clean oxygen sensor bung threads
   Using a wire brush, clean the threads in the exhaust pipe oxygen sensor bung. Remove any carbon buildup, rust, or old anti-seize compound. Ensure threads are clean and undamaged to allow proper seating of the new sensor.
7. 7

   Prepare new oxygen sensor
   Apply a thin coating of anti-seize compound to the threads of the new oxygen sensor. Apply only to the threads - do not allow anti-seize to contact the sensor tip or vent holes as this will damage the sensor. Use nickel-based anti-seize rated for exhaust temperatures.
   ⚠Excessive anti-seize or contamination of the sensor element will cause immediate sensor failure and false readings.
8. 8

   Install new oxygen sensor
   Thread the new oxygen sensor into the exhaust bung by hand, ensuring it threads smoothly without resistance. Once hand-tight, use the oxygen sensor socket and torque wrench to tighten to specification. Route the sensor wire away from hot exhaust components.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
9. 9

   Secure oxygen sensor wiring
   Route the sensor wiring harness following the factory wire path. Secure the wiring in all original retaining clips and brackets. Ensure adequate clearance from hot exhaust components, sharp edges, and moving suspension parts.
10. 10

    Reconnect oxygen sensor electrical connector
    Connect the oxygen sensor electrical connector, ensuring it clicks into place securely. Verify the connector lock tab is fully engaged and the connection is weather-tight.
11. 11

    Reconnect battery and clear codes
    Reconnect the negative battery cable. Start the engine and verify no exhaust leaks are present at the oxygen sensor location. Use a scan tool to clear any stored diagnostic trouble codes related to the oxygen sensor.

Reassembly

1. If both downstream sensors were replaced, repeat steps 2-10 for the opposite bank before reconnecting the battery
2. Ensure all wiring is properly routed and secured away from heat and moving parts
3. Lower vehicle from jack stands once verification is complete

Verification

• Start engine and listen for exhaust leaks at the oxygen sensor location - there should be no hissing or ticking sounds
• Allow engine to reach operating temperature and verify the oxygen sensor is providing data using a scan tool
• Monitor for diagnostic trouble codes - codes P0136, P0137, P0138 (Bank 1) or P0156, P0157, P0158 (Bank 2) should not return
• Test drive vehicle for 10-15 minutes and verify proper engine performance and no check engine light illumination
• Perform a drive cycle to allow the powertrain control module to complete oxygen sensor readiness monitors

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