Fix It

There are two oxygen sensors integrated into the exhaust system of the 2001 Saturn SL. The sensors help the 1.9-liter four-cylinder engine generate an ideal fuel-to-air ratio for optimum emissions. One sensor is located near the manifold and monitors this mixture. If the mixture becomes compromised (too much air makes the mix too lean; too much fuel makes the mix too rich), the sensor transmits a trouble code to the computer in the car. The rear sensor monitors the efficiency of the catalytic converter, which filters the harmful exhaust gases and converts them into less-harmful emissions.

Instructions

Upstream Sensor

1

Start the engine of the Saturn on a level ground for at least five minutes to warm the engine. This will help expand the metal of the manifold and sensor junction. Be caul and dont let it run too long, because it wont take long for the manifold and sensor to get hot enough to burn you.

2

Open the hood and locate the upstream sensor at the bottom of the manifold in the front of the engine. Disconnect the wire harness plug connection.

3

Spray penetrating lubricant along the threads of the sensor where it screws into the manifold and allow it to soak in for a few minutes.

4

Place the socket onto the ratchet and place the sensor wire into the slot of the socket (or feed the wire through the box end of a 22mm wrench) and turn the sensor counterclockwise to remove it from the manifold.

5

Inspect the new sensor before inserting it into the port hole in the manifold. Most quality aftermarket sensors have a light coat of high-temperature anti-seize compound on the threads of the sensor. If there is none on the threads, apply a very light coat to the threads only. Avoid getting any on the sensor itself.

6

Thread the sensor into the manifold porthole by hand, then tighten snugly. Do not over-tighten the sensor or youll strip the few threads it has and will ruin it. Plug the wire from the new sensor back into the wire-harness connector.

Downstream Sensor

7

Park the Saturn on a hard, level surface and then apply the parking brake (after warming the engine for five minutes; again, this will expand the metal of the exhaust pipe and sensor junction). Use the vehicle jack to lift the front of the Saturn, one front quarter panel at a time, high enough to place a jack stand under each front frame rail.

8

Put on safety glasses and crawl underneath the Saturn with the remaining items.

9

Locate the downstream sensor near the catalytic converter (in the center of the undercarriage under the front seats of the passenger cab).

10

Disconnect the wire-harness connection, then spray the threads with penetrating lubricant. Allow a few minutes to let the spray soak in. Use the ratchet and socket or 22mm wrench as described in Step 4 of Section 1 to remove the sensor from the exhaust piping.

11

Insert the new sensor (again making sure it has a light coat of high-temperature anti-seize compound on the thread section only) into the porthole of the exhaust pipe, and tighten snugly. Reconnect the wire of the sensor to the harness plug connection.

The oxygen sensors in a 1996 Ford Explorer gauge the amount of unburned oxygen present in the exhaust system. A signal is sent to the engine management computer. The unburned oxygen relates to the fuel mixture, and the computer makes continuous adjustments as a result of these signals. There are always at least two sensors on each exhaust system. If the vehicle has dual exhaust, it will have four sensors.

Instructions

1

Connect the code scanner cable end to the OBD port under the dash on the left side of the steering column. The scanner is needed to determine which sensor is defective. Turn the ignition key to the "Run" or "On" position.

2

Press the key marked "Read." The computer will display a five-digit code. Record this code. Cross-erence this code with the code sheet that accompanies the code scanner to identify the faulty sensor. Turn the key off.

3

Raise the vehicle with the floor jack and place jack stands under the frame. Lower the vehicle onto the jack stands. Disconnect the electrical connector from the faulty sensor. If the code indicated that the number 1 sensor is faulty, it will be the one between the engine and the converter. If the number 2 sensor is faulty, it will be the sensor on or behind the converter.

4

Remove the faulty sensor using the 7/8-inch wrench. Turn the sensor counterclockwise to remove it.

5

Install the new sensor and tighten with the wrench. Connect the electrical connector. Lower the vehicle with the floor jack.

The oxygen sensor on your 1996 Jeep Cherokee helps regulate the fuel consumption and emissions. The sensor is threaded into the exhaust manifold and monitors the oxygen saturation in the trucks exhaust. The Cherokees computer adjusts the fuel-and-air mixture combusted in the engine based on the oxygen saturation. If your truck begins to burn a noticeably greater amount of fuel compared to its normal fuel consumption, buy a replacement oxygen sensor from an auto parts store and change it at home.

Instructions

1

Lift the front of the Cherokee with a jack until it sits high enough to fit jack stands underneath it for support. Place the jack stands under the frame rails just behind the front wheels. Lower the Cherokee so that it rests securely on the jack stands.

2

Disconnect the electrical connection from the oxygen sensor. Remove the sensor with a wrench or oxygen sensor socket attached to a ratchet.

3

Spread a thin layer of anti-seize compound on the threads of the new sensor. Do not get anti-seize compound on the sensor head. Thread it into place by hand. Tighten the sensor with a wrench or a socket and ratchet.

4

Connect the wiring harness connection by pressing it together until it clicks. Lift the truck with the jack until you can remove the jack stands. Return the truck to the ground.

Depending on the year of the Ford Taurus, there may be two or more oxygen sensors present in the exhaust system. In the common 3.0-liter 6-cylinder models, there are four sensors. Read and diagnose the trouble code that set off the "check engine" light to ensure youre replacing the correct sensor.

Instructions

1

Drive the Taurus onto a car lift. Put on safety glasses and crawl underneath the car.

2

Locate the sensor you need to replace. Two of them are screwed into each side of the Y-pipe coming off each manifold; there are two more downstream located after each catalytic converter.

3

Unplug the oxygen sensor from the wire harness.

4

Remove the oxygen sensor, using socket and ratchet. If necessary, heat up the pipe surrounding the oxygen sensor with a torch for easier extraction. Allow the pipe to cool down before continuing.

5

Apply a light coat of anti-seize lubricating compound to the threads of the new oxygen sensor. Be caul not to get any of the compound onto the head of the sensor.

6

Thread the sensor into the porthole of the exhaust pipe. Tighten with the ratchet and oxygen sensor socket.

7

Plug the oxygen sensor wire back into the wiring harness.

A Tracker is a small sport utility vehicle that was sold under the GEO and Chevrolet nameplates from 1989 to 2004. The Chevrolet Equinox took the Trackers place in the 2005 model year. The oxygen sensor on your Tracker makes sure the correct air/fuel ratio is achieved by sending signals to the engines electronic computer module. Your engine will not run at its maximum efficiency if the oxygen sensor is not operating properly. The first step in replacing the oxygen sensor in your Tracker is to remove the old one.

Instructions

1

Set the parking brake. If the engine has been run recently, let it cool for a few hours before you begin.

2

Raise the vehicle with a hydraulic jack and place jack stands under your Trackers frame to support its weight. Lower the hydraulic jack and set it aside.

3

Crawl under the vehicle on the right hand side (drivers side) near the drivers door. Locate the catalytic converter, which is mounted in-line with the exhaust pipe.

4

Locate the oxygen sensor which is mounted in the exhaust pipe near the rear of the catalytic converter.

5

Remove the wiring harness connector from the oxygen sensor by squeezing in the connector tabs with your fingers while simultaneously pulling the connector from the sensor.

6

Remove the sensor from the exhaust pipe by turning it out with an adjustable wrench in a counterclockwise direction.

The Chevy Blazer has the same 4.3 liter engine, the same chassis and the same exhaust components from 1994 to 1999. This includes the two oxygen sensors. The bank one sensor is located on the left side (drivers side) of the front exhaust Y-pipe. The bank two sensor is located just before the catalytic convertor in the exhaust pipe. Which oxygen sensor needs to be replaced will require an OBD II (On Board Diagnostics II) computer code reader or scan tool to determine the culprit. They are removed the same way, but the bank two sensor is much easier to get to. However, the parts and labor estimate may to replace the sensor may help you decide to take on the job yourself with just a few tools.

Instructions

1

Drive the 1999 Blazer up on car ramps to raise the front end. If you do not have car ramps, lift the front of the Blazer on a flat, level paved or concrete surface using a floor jack and two jack stands placed under the front frame rails. Apply the parking brake.

2

Place a wheel chock behind one of the rear wheels.

3

Put on the safety glasses and crawl under the Blazer (on a creeper if you have one) and bring the remaining tools with you.

4

Locate the oxygen sensor to replace. The bank one sensor is up under the left drivers side just forward of the front exhaust Y-pipe. The bank two sensor is located in the exhaust pipe just forward of the catalytic converter.

5

Follow the wire harness plugged into the oxygen sensor youre replacing. Using the small straight edged screwdriver, press in the lock clip of the plug and unplug the oxygen sensor wire from the harness.

6

Place the 22 millimeter wrench or oxygen sensor socket and ratchet onto the oxygen sensor and turn it to the left to release it. If it does not want to release, light the hand held portable propane torch and heat the exhaust pipe around the edge of the oxygen sensor. Do not heat the oxygen sensor, too. Just the pipe around it. Try to loosen the sensor until youre successful. If you had to use the torch, allow the exhaust pipe to cool down and just take a break.

7

Apply a light coat of high-temperature anti-seize lubricant to the threads of the new oxygen sensor only if there is not already some on them.

8

Screw the new oxygen sensor into the port. Tighten with the wrench or socket and ratchet. Do not over-tighten. The sensor only has about 4 to 5 threads and stripping those threads would be futile to the sensor.

9

Plug the sensor wire back into the wire harness.

10

Collect all the tools and debris from under the Blazer. Remove the wheel chock and lower the Blazer.

When one of the multiple oxygen sensors detect a lean mix of burned fuel to oxygen ratio or a bad circuit relay in your Ford Explorer Sport Trac, it will trip the "check engine" light. Finding the faulty sensor will require having the computer of the Explorer scanned. You can purchase quality aftermarket direct-fit oxygen sensors from parts stores now and many will be glad to scan the computer for free in order to sell your the parts you need.

Instructions

1

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.

2

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.

3

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.

4

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.

5

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

6

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

7

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.

The job of your Volvo S80s oxygen sensor is to regulate the fuel and air ratio in your car. It also controls your gas mileage. If the oxygen sensor malfunctions, your S80 will run poorly, and its gas mileage will decline. With a few tools, most people can replace the oxygen sensor safely.

Instructions

1

Locate the oxygen sensor on your pre-catalytic converter. It is near the right front wheel well of your S80.

2

Detach the two small air intake pipes by hand from the air box and from the blowoff valves. Twist off the large air intake pipe as well from the air box and the rear turbo. This provides access to the oxygen sensor. Spray WD-40 over the existing oxygen sensor to make it easier to remove.

3

Use the 7/8-inch wrench to remove the failed sensor. Locate the stock sensor wire near the engine lift loop near your engines firewall. Connect the ends of the stock sensor wire to the new oxygen sensors wires using the crimp connectors.

4

Rub a small amount of anti-seize paste onto the new oxygen sensor threads. Do not get any paste on the sensor itself, because that could cause it to fail. The paste will make removal easier the next time.

5

Screw in the new oxygen sensor, and tighten it enough with the wrench that it cannot be loosened easily. Reattach the air pipes to the valves.

The oxygen sensors in your 1998 Honda Accord help regulate the fuel consumption of your car. When an oxygen sensor fails, your car begins to burn too much fuel and you gas mileage declines dramatically. The 1998 Accord contains two oxygen sensors located in the exhaust pipe on either end of the catalytic converter. It is best to replace both together to avoid having another one fail immediately after the first replacement. Buy replacement sensors from an auto parts retailer or Honda dealer.

Instructions

1

Raise your 1998 Honda Accord with a jack and secure it on a set of jack stands. Position the car high enough to work comfortably beneath it.

2

Locate the oxygen sensor you want to change. Disconnect the electrical connection at the top of the sensor. Squeeze the retaining clip and pull the wiring connector straight off the sensor.

3

Remove the oxygen sensor from the exhaust pipe using an oxygen sensor socket and ratchet. Insert the new oxygen sensor by hand to prevent cross threading the new sensor. Torque the sensor to 33 ft.-lbs. with your torque wrench.

4

Reconnect the wiring harness on the new oxygen sensor. Press the electrical connection straight onto the new sensor until it clicks.

5

Repeat the process on the other sensor if needed. Raise the car with the jack and remove the jack stands. Lower the car to the ground.

Modern automobiles rely on sophisticated computerized engine management systems that include fuel injection, and monitor the air/fuel ratio by means of oxygen sensors in the exhaust system. Thus, oxygen sensors are an integral part of the engine system.

Air/Fuel Ratio

The air/fuel ratio for a gasoline engine has an optimal value of 14.7 to 1. This ratio results in good performance, and also reduces harmful emissions such as carbon monoxide and nitrogen oxides. Oxygen sensors monitor and maintain this critical ratio.

Performance and Emissions

Too much fuel in the air/fuel mix results in a "rich" mixture, and produces excessive unburned hydrocarbon emissions. Too little fuel results in a "lean" mixture, which produces excessive nitrogen oxide emissions. The fuel/air mix changes in response to data from the oxygen sensors, which monitor these emissions to make sure that the mix is neither too rich nor too lean.

Computer Management

A properly functioning engine management system uses fuel injection metering, a computer program and emissions sensors to ensure optimal engine performance, and the lowest possible level of harmful emissions, under a wide variety of operating conditions.