How to Change an Oxygen Sensor on Ford Cars

by Contributing Writer

There are at least two sensors on the Ford car. One sensor is in front of the catalytic converter, and the other is behind it. Oxygen sensors check the amount of unburned oxygen going in the Ford car converter as opposed to coming out. This will calculate how well the converter is functioning and if the engine is using the correct fuel ratio. Any problem with the ignition system, intake manifold leaks, timing, condition of the internal engine components, or any of the sensors will result in a ambiguous reading on the oxygen sensor, turning the "Check Engine" light on. The oxygen sensor reading is a direct result of all of these items if they are malfunctioning. All of these must be checked first, because the only way the computer has of checking the oxygen sensor is through its signal. If all the above is all right, then the sensor itself is malfunctioning.

Under The Hood:

 How to Change an Oxygen Sensor on a Ford Escort

Open the hood on your Ford Escort and disconnect the negative battery cable from the battery. Place it to the side of the battery so that it cannot fall and accidentally allow the battery to connect and the engine to start.

Locate the oxygen sensor. On a Ford Escort, the sensor may be found either on the exhaust manifold, where the exhaust pipe enters the engine block, or it is attached directly in the header pipe beneath the exhaust manifold. The oxygen sensor will look like a cylindrical plug sticking out from the manifold or pipe with a #4 wire attached to the very top.

Disconnect the wire by gently pinching it between your fingers as close to the sensor tip as possible and pulling the connection apart.

Crack the sensor loose by putting a 7/8 wrench on the sensor so the wrench is firmly on the nut of the sensor and lightly tapping the handle of the wrench with a hammer until the sensor and the wrench move. The nut of the sensor looks similar to a regular nut but it is molded as part of the sensor body.

Use the wrench to unscrew the sensor and remove the sensor.

Spray a short blast of carburetor cleaner in the sensor hole and follow this with a short burst of air from your can of compressed air to clean out the hole.

Take your new oxygen sensor and insert it into the hold. Hand tighten the sensor with the 7/8 wrench.

Attach the #4 wire to the top of your new sensor.

Reconnect the negative battery cable to the battery and close the hood of the engine.

Items you will need

  • 7/8 wrench

  • Carburetor cleaner

  • Compressed Air (can)

 How to Replace the Oxygen Sensor on a Ford Windstar

Jack up the Windstar using the front jack point behind the radiator.

Place jack stands under the front pinch welds of the vehicle and lower the Windstar onto the stands.

Climb under the car and locate the oxygen sensor on the catalytic converter. It will look like a small plug sticking out of the exhaust towards the front of the vehicle.

Disconnect the electrical leads running to the oxygen sensor.

Unbolt the sensor using the oxygen sensor socket and a socket wrench.

Install the new sensor. Installation is the reverse of removal.

Items you will need

  • Jack

  • Jack stands

  • Socket wrench

  • Oxygen sensor socket

  • Replacement oxygen sensor

 Replace an Oxygen Sensor on a Ford Taurus

Install the code scanner to the OBS port under the Ford Taurus' driver's side dash. Turn the ignition key on, and the scanner will display the word "Read." Press the button for "Read," and the scanner will display the codes. Write the code or codes down and look for the corresponding explanation of the codes, which is displayed in the form of a number, in the chart provided with the scanner. If it states that sensor 1 or sensor 2 is not giving a proper signal, then the first one is before the converter and the second after the converter.

Correct the other codes first, then hit "Erase" on the scanner to clear the codes, and recheck with the engine running to see if the code comes back. If there were other codes, it is entirely possible that other issues caused the mixture to be wrong, causing the computer to set a code for the oxygen sensor. Oxygen sensors are not cheap and respond directly to the activity of the engine weather, good or bad, with a corresponding signal. If the oxygen sensor code still shows up, go to Step 3.

Raise and support the vehicle on jack stands. Disconnect the wiring harness at the pig tail for the sensor. Remove the oxygen sensor with the appropriate wrench or socket.

Brush anti-seize compound on the threads of the new sensor and tighten it in its socket on the vehicle. There is no need to crank down on the sensor; just make sure it is tight. Plug the electrical connector into the new oxygen sensor.

Turn the key on and hit the "Erase" button on the scanner; it will turn the "Check engine" light off on the dash and erase the code.

Items you will need

  • OBD code scanner 7/8-inch Open end wrench 7/8-inch Deepwell oxygen sensor removal socket ½-inch Drive ratchet Floor jack Jack stands

 How to Replace the Oxygen Sensor on a Ford Explorer Sport Trac

Raise the front end of the Explorer Sport Trac by driving it up onto car ramps. Apply the parking brake and place a wheel chock behind one of the rear tires.

Put on the safety glasses and gather the tools, replacement sensor and creeper if you have one. Crawl under the front of the Explorer Sport Trac.

Locate the sensor to be replaced. These sensors are screwed into the exhaust pipes and components and wired to wire harnesses that communicate to the computer system of the Sport Trac. The information of which sensor to replace should have already been obtained. Follow the exhaust piping from the engine manifold back until you have located the correct sensor.

Locate the sensor wire outlet plug. Some of the sensors on the Sport Tracs have a tricky plug to get at. Remove the plastic plug clip from the frame of the Sport Trac by prying it out with the screwdriver, but be careful not to damage the wire harness side of the outlet. Unplug the oxygen sensor wire from the wire harness.

Use the ratchet and socket to remove the sensor. Place the sensor wire into the slot on the side of the socket.

Screw in the new oxygen sensor and tighten. Be careful not to over-tighten or you could damage the threads to the new sensor.

Plug the oxygen sensor wire into the wire harness and fasten it back to the frame if you removed it. Gather the tools and creeper and crawl out from under the Sport Trac. Remove the wheel chock and back the Sport Trac off of the ramps.

Items you will need

  • Safety glasses

  • Car ramps

  • Wheel chock

  • Flathead screwdriver

  • Creeper (optional)

  • 3/8-inch drive ratchet

  • 3/8-inch drive oxygen sensor socket

  • Direct-fit oxygen sensor replacement

 How to Replace the Oxygen Sensor on a Ford

Remove the negative battery cable from the battery. This will disable the Ford car's electrical system.

Use the car jack and raise the vehicle high enough so you can comfortably reach the underside of the Ford vehicle.

Place the jack stand under the outer edge of the car frame to additionally support the vehicle. Never rely on a car jack alone to support the heavy weight of a vehicle. Always use one or two jack stands in addition to the car jack.

Locate the O2 sensor and spray the area around the threads with the spray lubricant. The lubricant will take a few minutes to soak in and will help in loosening the tight-fitting sensor.

Disconnect the electrical plug from the sensor.

Use the special sensor tool or the 7/8-inch or 22-mm end wrench and remove the sensor from the exhaust pipe.

Coat the threads of the new oxygen sensor liberally with the anti-seize compound. This will aid in the installation of the new sensor by lubricating the threads.

Install the new sensor with the tool or end wrench.

Reconnect the electrical plug to the sensor.

Remove the jack stands and lower the car to the ground with the jack. Replace the negative battery terminal and start the car.

Items you will need

  • Car jack Jack stand Spray lubricant Sensor tool or a 7/8-inch or 22-mm open-end wrench New oxygen sensor Anti-seize compound

 How to Replace an Oxygen Sensor on a Ford Truck

Locate the fender well liner on the front passenger wheel well of your Ford truck and disconnect the liner by undoing the screws with a screwdriver and pulling the liner away from the plastic connectors until you can pull it free of the wheel well.

Turn your steering wheel all the way to the left so that you have room to access the oxygen sensor without having to remove the tire.

Disconnect the negative battery cable from the battery using an open-end wrench and move the cable out of the way.

Locate the transmission dipstick on the back of the engine near the firewall and take the dipstick out of the tube, setting it aside in a safe place.

Find the transmission tube from underneath the truck that goes into the transmission and find the oxygen sensor that is sitting right next to the transmission tube.

Locate the bolt that is holding the transmission tube to the engine block with a bracket and use a socket wrench to unfasten the bolt.

Pull the transmission tube straight out of the transmission by hand and move it out of the way.

Disconnect the wiring on the end of the oxygen sensor by using a screwdriver to undo the clip holding the wiring connectors together.

Remove the oxygen sensor by using an oxygen sensor socket and wrench and carefully undo the sensor so that it doesn't crack while it's being removed.

Position the new oxygen sensor and tighten it in place using the oxygen sensor socket and wrench and reattach the wiring connectors for the oxygen sensor.

Slide the transmission tube into the transmission and attach the tube to the engine block, securing the bolt with a socket wrench.

Place the transmission dipstick back into the tube and attach the negative battery cable on the battery with an open-end wrench.

Reattach the wheel well liner under the front passenger wheel, securing the plastic clips and using a screwdriver to fasten the screws.

Items you will need

  • Screwdriver

  • Open-end wrench

  • Socket wrench set

  • Oxygen sensor socket

 How to Replace the Oxygen Sensor on an F-150

Raise the front end of your truck with a jack. Position a set of jack stands under the frame to support it. Locate the oxygen sensors in the exhaust system. You will find one in the pipe just behind the catalytic converter; two others will be further back where the pipe splits before the mufflers.

Disconnect the wiring harness from the front-most sensor by pulling the locking tab on the connector toward you and then sliding the two sections of the connector apart. Do not pull on the wires or you may damage the wiring harness.

Remove the oxygen sensor from the pipe by turning it counterclockwise with a ratchet and oxygen sensor socket. Pull the sensor from the exhaust pipe.

Install the new oxygen sensor into the exhaust pipe. Turn it clockwise with a ratchet and oxygen sensor socket until snug. Tighten the sensor to 36 foot-pounds with a torque wrench.

Install the wiring harness connector. Push the locking tab into the connector to secure it. Move to the downstream sensors and repeat the process to change both of these oxygen sensors as well.

Items you will need

  • Jack

  • Jack stands

  • Oxygen sensor socket

  • Ratchet

  • Torque wrench

 How to Replace the Oxygen Sensor on a 2003 Ford Expedition

Park the Expedition on level ground and set the parking brake.

Raise the front of the Expedition and support it with jack stands on each side of the frame.

Trace the exhaust pipes back from the engine toward the rear of the Expedition. There is a pipe on each side of the engine. They will join into one pipe as you go toward the rear. You will see the sensors sticking out of the exhaust pipes at the 2 o'clock position on the driver's side and the 10 o'clock on the passenger's side pipes just before the pipe bends into the "Y" where the two pipes become one.

Disconnect the oxygen sensor at the electrical connector to the wiring harness. The sensor has a 6-inch lead wire connected to it.

Place the oxygen sensor socket on the sensor by sliding the sensor's electrical lead into the slot in the socket, then placing the socket over the metal part of the sensor. Turn counterclockwise to remove the sensor.

Install the new oxygen sensor by screwing it into the hole in the exhaust pipe. Place the electrical lead in the slot and place the socket over the sensor and tighten. Connect the lead to the wiring harness.

Items you will need

  • Jack

  • Jack stands

  • Ratchet

  • Oxygen sensor socket

 How to Replace the Oxygen Sensor on a Ford 5.4

Allow the engine to cool for an hour prior to working on the exhaust. Lift the truck into the air using the jack and put it down onto the jack stands.

Locate the oxygen sensors on the exhaust. They are on the exhaust, just where the exhaust connects to the exhaust manifolds, by the firewall of the truck. Unplug the wiring harnesses on the sensors and remove the sensors using the oxygen sensor wrench.

Use the applicator provided with the anti-seize compound to apply anti-seize compound to the threads of the replacement oxygen sensors. Be very careful not to get any of the compound on the sensor body itself.

Install the sensors into the exhaust using the oxygen sensor wrench, then connect the electrical harnesses using your hands.

Items you will need

  • Jack

  • Jack stands

  • Oxygen sensor wrench

  • Anti-seize compound

  • Replacement oxygen sensors