Heated Oxygen Sensor Replacement

• 1). Raise the front of the Explorer, using a floor jack, and position jack stands under the SUV's frame rails. Lower the Explorer onto the jack stands.
  
  
• 2). Crawl beneath the vehicle and locate the two catalytic converters -- the two muffler-like exhaust components near the middle of the SUV. Look on the exhaust pipe in front of each catalytic converter and locate the heated oxygen sensor screwed into each exhaust pipe.
  
  
• 3). Trace the heated oxygen sensor's wiring upward until you reach where the sensor's wiring harness connects to the Explorer's wiring harness. Press the locking button and pull the sensor's harness from the vehicle's harness.
  
  
• 4). Remove the heated oxygen sensor, using a ratchet and oxygen sensor socket. Hand-thread a new oxygen sensor into the exhaust pipe and tighten it to 30 foot-pounds, using a torque wrench and oxygen sensor socket. Plug the oxygen sensor's wiring harness into the Explorer's wiring harness.
  
  
• 5). Repeat Steps 3 and 4 for the other heated oxygen sensor, if needed.
  
  
• 6). Raise the SUV off the jack stands, using a floor jack, and remove the jack stands. Lower the truck to the ground.
  
  

Catalyst Monitor Sensors

• 1). Raise the front of the Explorer, using a floor jack, and position jack stands under the SUV's frame rails. Lower the Explorer onto the jack stands.
  
  
• 2). Crawl beneath the vehicle and locate the two catalytic converters -- the two muffler-like exhaust components near the middle of the SUV. Look on the exhaust pipe to the rear of each catalytic converter and locate the catalyst monitor sensor screwed into each exhaust pipe.
  
  
• 3). Follow the heated oxygen sensor's wiring upward until you find where the sensor's wiring harness connects to the vehicle's wiring harness. Press the locking button and pull the sensor's wiring harness from the Explorer's wiring harness.
  
  
• 4). Remove the catalyst monitor sensor, using a ratchet and oxygen sensor socket. Hand-tighten a new catalyst monitor sensor into the exhaust pipe behind the catalytic convertor, and tighten it to 30 foot-pounds with a torque wrench and oxygen sensor socket. Plug the catalyst monitor sensor's wiring harness into the Explorer's wiring harness.
  
  
• 5). Repeat Steps 3 and 4 for the other catalyst monitor sensor, if needed.
  
  
• 6). Raise the SUV off the jack stands, using a floor jack, and pull the stands from under it. Lower the Explorer Sport Trac to the ground.