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How to Install a 2003 Ford Escape Oxygen Sensor

by Justin Cupler

Automotive emission regulations effectively removed the “muscle” from the muscle cars of the 1960s and early-1970s. Throughout the following years, however, automotive engineers continued developing ways around the emissions, and vehicles are now producing more horsepower-per-liter than ever before, even compared to the muscle car era. One of the advances in automotive emissions was the introduction of oxygen sensors, which monitor the amount of toxic emissions as they travel from the engine and through the exhaust. The 2003 Ford Escape has two types of oxygen sensors: heated oxygen sensors, which are commonly called upstream sensors, and catalyst monitors, which are commonly called downstream sensors. Replacing the sensors is a straightforward task once you locate them.

Heated Oxygen Sensor on the 2.0-Liter Engine

1

Allow the vehicle to cool, if you drove it recently.

2

Remove the four bolts securing the heat shield to the exhaust manifold, using a ratchet and socket. Pull the heat shield from the engine compartment.

3

Press and hold the unlocking button on the heated oxygen sensor’s wiring harness, and unplug it from the Escape’s wiring harness.

4

Trace the heated oxygen sensor’s wiring downward until you reach the spot where the sensor plugs into the manifold.

5

Remove the oxygen sensor from the manifold, using a ratchet and oxygen sensor socket. If the sensor is seized in the manifold, spray it with a rust-penetrating chemical and allow it to set for the period of time specified by the chemical’s instructions, then remove the sensor.

6

Apply a thin coat of an anti-seize chemical meeting Ford specification ESE-M12A4-A, then hand-thread the sensor into the manifold. Tighten the heated oxygen sensor to 30 foot-pounds with a torque wrench and oxygen sensor socket.

7

Plug the new oxygen sensor’s wiring harness into the Escape’s harness.

8

Reinstall the manifold heat shield and hand-thread its retaining bolts. Torque the heat shield bolts to 8 foot-pounds with a torque wrench and socket.

Catalyst Monitor on the 2.0-Liter Engine

1

Allow the vehicle cool, if needed. Unplug the catalyst sensor’s wiring harness from the Escape’s wiring harness, which is accessible from under the hood, by pressing and holding the unlocking button on the sensor’s harness and pulling it from the Escape’s harness.

2

Raise the front of the Escape off the ground with a floor jack and slide jack stands under its subframe. Lower the SUV onto the jack stands.

3

Crawl beneath the vehicle and find the catalytic converter just past the exhaust manifold; the catalyst monitor is located just past the catalytic converter, in the exhaust pipe.

4

Remove and install the new catalyst monitor by following steps 5 through 7 in the section titled “Heated Oxygen Sensor on the 2.0-Liter Engine.”

5

Raise the SUV off the jack stands with a floor jack and remove the jack stands. Lower the Escape to the ground.

Heated Oxygen Sensor on the 3.0-Liter Engine's Right Bank

1

Allow the engine to cool off, if recently driven.

2

Look on the exhaust manifold nearest the rear of the engine compartment and find the heated oxygen sensor screwed into it.

3

Trace the sensor’s wire upward until you reach its wiring harness. Press and hold the unlocking button on the wiring harness and unplug the sensor’s harness from the Escape’s harness.

4

Remove and install the new oxygen sensor by following steps 5 through 7 in the section titled “Heated Oxygen Sensor on the 2.0-Liter Engine.”

Heated Oxygen Sensor on the 3.0-Liter Engine's Left Bank

1

Wait for the engine and exhaust to cool prior to beginning, if needed.

2

Raise the front of the Escape with a floor jack and slide jack stands under its frame rails. Lower the SUV onto the frame rails.

3

Crawl beneath the Escape and find the catalytic converter coming off the front exhaust manifold pipe. Look on the exhaust manifold side of the catalytic converter and find the heated oxygen sensor screwed into the exhaust pipe.

4

Unplug, remove and install the new left bank heated oxygen sensor by following steps 2 and 3 in the section titled “Heated Oxygen Sensor on the 3.0-Liter Engine's Right Bank.”

5

Raise the Escape off the jack stands with a floor jack and remove the jack stands. Lower the SUV to the ground.

Catalyst Monitor on the 3.0-Liter Engine's Right Bank

1

Allow the Escape to cool until the engine feels cool to the touch, if needed.

2

Look under the hood, just behind the engine oil dipstick and find the oxygen sensor wiring harness. Press and hold the unlocking button on the harness, and unplug it from the Escape’s harness.

3

Raise the front of the SUV with a floor jack and slide jack stands under the subframe. Lower the vehicle onto the jack stands.

4

Crawl beneath the Escape and trace the rear exhaust manifold downward until you reach the catalytic converter. Find the catalyst monitor screwed into the pipe, just past the catalytic converter.

5

Remove and install the new catalyst monitor follow steps 5 through 7 in the section titled “Heated Oxygen Sensor on the 2.0-Liter Engine.”

Catalyst Monitor on the 3.0-Liter Engine's Left Bank

1

Park the vehicle and allow it to set until the engine and exhaust are cool to the touch.

2

Lift the front of the Escape with a floor jack and slide jack stands under its frame rails. Lower the SUV onto the jack stands.

3

Crawl under the SUV, then look on the exhaust pipe just past the catalytic converter and find the catalyst monitor screwed into the pipe.

4

Unplug, remove and install the catalyst monitor follow steps 2 and 3 in the section titled “Heated Oxygen Sensor on the 3.0-Liter Engine's Right Bank.”

5

Raise the vehicle off the jack stands with a floor jack and remove the jack stands. Lower the Escape to the ground.

Items you will need

References

About the Author

Justin Cupler is a professional writer who has been published on several websites including CarsDirect and Autos.com. Cupler has worked in the professional automotive repair field as a technician and a manager since 2000. He has a certificate in broadcast journalism from the Connecticut School of Broadcasting. Cupler is currently studying mechanical engineering at Saint Petersburg College.

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