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Mercedes-Benz vehicles are well known for their prestige and luxury, but despite their high reputation, they still encounter problems from time-to-time. One of the more common problems that can occur with a 2001 Mercedes-Benz SLK 320 is a faulty crankshaft position sensor. The most noticeable symptom of a faulty crankshaft position sensor on a 2001 SLK 320 is an engine that cranks but wont start. This is because the powertrain control module, or PCM, cannot determine when to fire the spark plugs inside the engine cylinders. Because the crankshaft position sensor is a non-serviceable part, it must be replaced when faulty.

Instructions

Removal

1

Engage the parking brake and open the hood. Remove the plastic engine paneling by lifting up on it until it pops loose.

2

Pull the intake tube out of the air cleaner box, and then remove the intake tube from the throttle body outlet by gently pulling on it. Pull the air cleaner housing off of the cylinder head cover and then remove the entire air cleaner assembly from the engine bay.

3

Locate the crankshaft position sensor on the back side of the engine block, next to the transmission bell housing, between the firewall and the left cylinder head. The sensor is black and has a single black wire connector attached to it.

4

Disconnect the sensors electrical connector and remove the bolt holding the sensor to the engine block. Pull the sensor out of the engine block. If it stubborn, caully remove it using a slip-joint pliers, moving slowly to ensure that the sensor doesnt break off inside the block.

Installation

5

Grease the sensor with a small amount of clean engine oil and insert it into the block until its fully-seated. Reinstall the sensors retaining bolt and tighten it to 71-inch pounds with a torque wrench.

6

Reconnect the crank sensors electrical connector.

7

Set the air cleaner assembly into position and press it down on top of the cylinder head cover until it snaps into place. Reconnect the air cleaner tube to the air box and the throttle body air housing.

8

Place the plastic engine paneling in position on top of the engine and press down on it until it locks in place. Plug the Mercedes-Benz Star Diagnosis scan tool into the vehicles communication port and run the CKP re-sync procedure.

The 1989 model year brought a complete redesign of Nissans flagship sedan, the Maxima. Experts considered this version of the Maxima the most beautiful to date, and it was also significantly larger than previous models. The 1989 Maxima uses just one oxygen sensor to monitor the level of oxygen in the exhaust and send this information to the electronic control unit. The ECU then uses this information to adjust the air-to-fuel ratio in the combustion chamber to keep the Maxima at peak performance.

Instructions

Removal

1

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

2

Crawl under the middle of the vehicle and find the front pipe, the exhaust pipe just before the catalytic converter. Find the oxygen sensor screwed into the front pipe, just before the catalytic converter.

3

Spray the base of the oxygen sensor with penetrating oil and allow it to sit for the time specified in the penetrating oil instructions.

4

Trace the oxygen sensors wiring upward until you find where the sensors wiring harness plugs into the Maximas wiring harness. Unplug the oxygen sensors wiring harness.

5

Remove the oxygen sensor from the front pipe, using a ratchet and oxygen sensor socket.

Installation

6

Apply a coating of anti-seize compound to the new oxygen sensors threads and hand-tighten the sensor into the front pipe.

7

Tighten the sensor to 15 foot-pounds using a torque wrench and oxygen sensor socket.

8

Apply a small amount of dielectric grease to the inside of the oxygen sensors wiring harness and plug the sensors harness into the Maximas wiring harness.

9

Raise the vehicle off the jack stands and remove the stands. Lower the vehicle to the ground.

If the Check Engine light is on in your 1998 Toyota Sienna, the oxygen sensor may be the cause. The oxygen sensor reads the oxygen levels in the exhaust and reports those levels to your trucks computer. If the sensor is failing, you may notice a decrease in your fuel efficiency. If you suspect that your O2 sensor is bad, many auto parts stores will scan the computer to determine the cause of your Check Engine light.

Instructions

1

Raise the truck using a jack and place it on a set of jack stands. Make sure it is raised enough to comfortably work under it.

2

Locate the oxygen sensor on the exhaust pipe just beyond the catalytic converter, toward the back of the truck. The sensor protrudes from the pipe on the passenger side of the vehicle.

3

Disconnect the electrical connection on the sensor. The connector should pull straight out of the sensor.

4

Remove the nuts on either side of the sensor using a socket and ratchet. Set the nuts aside in a safe place.

5

Remove the sensor from the pipe by pulling it straight out. Remove the gasket if it does not come out with the sensor.

6

Insert a new gasket and then insert the sensor into the mounting space on the exhaust pipe. Secure the sensor with the two nuts and tighten them with a socket and ratchet.

7

Connect the electrical connection to the sensor. The connector will plug straight into the sensor.

8

Raise the truck with a jack and remove the jack stands. Lower the vehicle to the ground.

The 1995 Pontiac Bonneville SSEI engine has one oxygen sensor that detects the oxygen saturation in the exhaust and relays the information to the engines computer to regulate the fuel consumption. When a sensor fails, the "Check Engine" or "Service Engine Soon" light may illuminate on your dash. If the light is on and your fuel mileage has significantly decreased, replace the sensor as soon as possible to save needless expense.

Instructions

1

Raise the hood of the Bonneville. Locate the oxygen sensor threaded into the exhaust manifold near the front of the engine compartment.

2

Pull the electrical connection apart to disconnect it from the sensor. Remove the sensor with a wrench.

3

Coat the threads of the new sensor with electrical anti-seize compound. Install it by hand to avoid cross-threading. Torque the sensor to 30 foot-pounds with a torque wrench.

4

Push the electrical connector together until it clicks. Lower the hood.

A camshaft sensor notifies a vehicles ignition module so it knows which of the engines cylinders is properly positioned to be fired. The location of camshaft sensors can vary. Having information on the location, as well as other facts regarding camshaft sensors, can benefit vehicle owners.

Location

Because a camshaft sensor may be magnetic, it will often be found positioned directly on the timing cover located over the gear of the camshaft. It can also be located either inside a special type of housing that takes the place of the distributor, or inside the distributor itself.

Functions

Some vehicle engines have distributorless ignition systems. When this is the case, a camshaft sensors role is to notify the motors control module of the position of the camshaft as well as the crankshaft. The information taken from the camshaft sensor is then used to assist with proper ignition timing.

Diagnosis

Many vehicles model year 1995 or newer can be checked for camshaft sensor problems using a scan tool. Once it is plugged in, the scan tool reveals certain fault codes if there is a problem. For example, fault code P0342 indicates low input in the camshaft sensors circuit.

The 1998 Chevy Blazer has three oxygen (O2) sensors. Two are located up on the front Y-pipe bolted to the V-6 engines manifold. These two sensors detect the fuel-to-air mix in the exhaust and transmit that information to the powertrain control module (PCM). From there, the PCM makes adjustments to achieve the lowest emissions possible while still running properly. The last O2 sensor is located after the catalytic converter. This sensors job is to monitor the efficiency of the catalytic converter.

Instructions

1

Apply the parking brake to lock the rear wheels.

2

Open the hood to the 1998 Chevy Blazer to allow some light down into the engine compartment. This will be helpful when under the vehicle to replace the front oxygen sensor(s). If you are replacing the rear sensor, opening the hood is not necessary.

3

Lift one front side of the Blazer up high enough to rest it on a jack stand and then lift the other side and rest that side on a jack stand.

4

Put on the safety glasses and crawl underneath the Blazer to locate the oxygen sensor(s) being replaced. One is located on the left-side Y-pipe up near the manifold connection, the other is on the right-side Y-pipe near the manifold and the rear sensor is located in the catalytic converter pipe just behind the shell of the converter.

5

Unlock the wire harness plug from the O2 sensor plug. Use the small screwdriver to press inward and release the lock while pulling the O2 sensor plug and wire away from the wire harness plug.

6

Spray penetrating oil around the threaded connection of the O2 sensor where it screws into the O2 sensor port of the exhaust piping. Allow the oil a few minutes to soak in.

7

Thread the O2 sensor wire through the closed end of the 22 mm wrench and then place the closed end of the wrench onto the sensors hex-head. Turn the wrench to the left (counterclockwise) to remove it from the port. Remove the sensor.

8

Inspect the threads of the replacement sensor. Most will come with a light coating of special anti-seize compound already on the threads. Some O2 sensor manufacturers will provide a small tube inside the box. If applying the compound, be sure to avoid getting the compound on the thimble-tip of the sensor. Only place a small amount on the threads of the sensor.

9

Thread the sensor into the port by hand to avoid crossing the threads of the sensor. Tighten the sensor with the wrench after threading the wire through the closed end again. Only tighten the sensor snugly. Over-tightening the sensor risks stripping the threads of the sensor and/or possibly damaging the threads to the sensor port.

10

Connect the replacement sensor wire plug to the wire harness plug before crawling out from under the Blazer with the tools and old sensor(s) and lowering the vehicle.

Oxygen Detection

The oxygen sensor informs a car computer of the level of oxygen being burned into the fuel. The computer utilizes this information to regulate the mixture of fuel to oxygen. Installing the oxygen sensor in the exhaust manifold allows the amount of O2 in the fuel mixture to be measured. A zirconium ceramic bulb (enameled in a layer of platinum with oxygen holes) is attached to the end of the oxygen sensor (At the end where the sensor is bolted into the exhaust manifold). Two leads platinum electrodes reside inside of the bulb. A very small amount of space is provided for the insulation and the wire. Air must be allowed to reach the oxygen sensor. When installing the oxygen sensor, no grease is used (grease inhibits the flow of oxygen to the sensor).

Heating

At a hot enough temperature the oxygen sensor will produce enough voltage to communicate with the car computer. Typically, the oxygen sensor will include a heating device inside of it. This heating device aids the oxygen sensor by quickly raising the operating temperature (600+ degrees Fahrenheit). Thus a signal to the car computer is produced in a timely manner. Older cars typically have a single lead (wire directly connected to the oxygen sensor) on the oxygen sensor and lack a heating device (operating temperature takes longer to reach). New cars typically possess a self heating oxygen sensor with three or more leads (multiple wires which are directly connected to the oxygen sensor). Over the years, the number of oxygen sensors in any new car has doubled.

Modern Sensor Systems

Modern cars have a second oxygen sensor installed in or behind the catalytic converter. This oxygen sensor monitors converter production. Bigger engines require one oxygen sensor to be installed per cylinder, and an additional oxygen sensor following a catalytic converter. Upstream/ downstream oxygen sensors are installed in many of todays newer cars to monitor emissions performance. This oxygen sensor ensures the converter minimizes pollution (exhaust). Converter failure prompts the malfunction indicator lamp to light up on the dashboard.

Tooling and Wiring

A 22-millimeter socket is used to remove the oxygen sensor from a car. The engine needs to be warmed up just a little bit before removing the oxygen sensor, otherwise the sensor may not budge. The socket is turned counter-clockwise over the bolt holding the sensor in place. Penetrating oil may be used around the bottom of the sensor to help loosen it from its fixture. Wiring on the connector fits all OEM oxygen sensors. Universal oxygen sensors, however, require the wiring connector to be cut. The wires are spliced to connect the connectors wires. Modern sensors typically have four wires (signal, ground, and two wires for the heater circuit. Color coding on a new sensor will not match leads on older converters.

Because oxygen sensors monitor the fuel-to-air mix ratio, most cars that did not integrate catalytic converters in their exhaust systems did not have oxygen sensors. The sensor not only regulates the fuel/air ratio, it also transmits the information to the powertrain control module (PCM) via a voltage signal and makes compensatory adjustments. The fifth-generation El Camino is the only design of the vehicle that used a combined catalytic converter-oxygen sensor emission control system.

Instructions

1

Lift the El Camino onto a car lift and bring it up to a comfortable height to work at from underneath. Put on the safety glasses before getting under the vehicle.

2

Locate the catalytic converter near the center of the El Caminos undercarriage and follow it to the front Y-pipe for the oxygen sensor.

3

Follow the wire coming from the oxygen sensor to the nearby wire harness plug. Unplug the sensor wire from the harness plug.

4

Spray the exposed threads of the sensor with a generous amount of penetrating oil.

5

Place the wire through the closed end of a box-end wrench and place the wrench on the hexagon-shaped base of the sensor. Turn the sensor counterclockwise to unthread it from the exhaust pipe. Remove the oxygen sensor. If necessary, apply heat to the exhaust pipe area and expand the metal of the pipe to help remove the sensor.

6

Apply a light amount of anti-seize compound on the threads of the replacement sensor. Do not let the compound come into contact with the sensors head.

7

Screw the sensor into the exhaust pipes porthole by hand and then snug it tightly with the wrench.

8

Plug the oxygen sensor wire back into the wire harness plug.

The 2005 Nissan Altima exhaust system includes two oxygen sensors. The upstream sensor is located near the exhaust manifold at the front of the exhaust system. The downstream sensor is located near the catalytic converter, further along the exhaust pipe. When a sensor fails, your "Check Engine" light will illuminate. If the "Check Engine" light is on and you notice a decrease in your fuel mileage, an oxygen sensor is the likely problem. Buy a replacement sensor from an auto-parts counter and change it at home in minutes.

Instructions

1

Lift the Altima using a jack until it is high enough to fit a set of jack stands under. Rest the car on the jack stands.

2

Locate the downstream oxygen sensor threaded into the exhaust pipe, approximately halfway down the car, below the center console area. Press the tab on the electrical connection while you pull the connectors apart to disconnect it.

3

Remove the sensor with a wrench or ratchet fitted with an oxygen sensor socket. Coat the new sensors threads with anti-seize compound, then hand-thread the sensor into the pipe.

4

Push the electrical connection together until it clicks. Remove the jack stands by lifting the car slightly with the jack. Lower the Altima to the ground.

The single oxygen sensor on the 1985 Chevy S-10 Blazer is a more primitive design than todays O2 sensors. Its erred to as a non-heated single (one) wired sensor. While it functions similarly to todays sensors, it demands that the engine is up to operating temperature, including the engine coolant, before it begins to monitor the fuel-to-air ratio. Todays sensors have multiple wires with built-in heaters that heat them up quickly to begin monitoring the emissions more readily. This lessens the amount of pollutants allowed into the air while the vehicle is warming up.

Instructions

1

Apply the parking brake of the 1985 Chevy S-10 Blazer and then open the hood. Access to the oxygen sensor is on the lower side of the engine, but youll have more adequate lighting with the hood opened.

2

Hoist one front quarter of the Blazer up with a jack placed under the frame rail and then lower the jack and Blazer onto a jack stand. Repeat for the other front quarter to elevate the front end completely.

3

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

4

Follow the front exhaust pipe to where it connects to the manifold on the drivers side to locate the oxygen sensor.

5

Follow the wire coming off the end of the oxygen sensor to the wire harness plug mating connection to the oxygen sensor plug. Lift up the release tab of the wire harness plug and then pull the oxygen sensor plug out.

6

Put the oxygen sensor socket onto the ratchet and then align the wire of the sensor into the slit on the side of the socket.

7

Place the socket fully onto the hex-head of the sensor and then turn the ratchet counterclockwise to remove it from the sensor exhaust port. Remove the sensor.

8

Inspect the replacement oxygen sensor threads. If there is no anti-seize compound on the threads, apply a thin coating of electrically conductive anti-seize compound to the threads, being caul not to get the compound on the head of the sensor.

9

Hand-thread the replacement sensor into the oxygen sensor exhaust port as far as it will go.

10

Tighten the sensor snugly with the ratchet and oxygen sensor socket (placing the sensor wire into the socket slit), but do not over-tighten it. The threads of the sensors are made of much softer metal than the exhaust system to prevent damaging the mating threads of the system. Because of this, its easy to strip the threads of the sensors.

11

Connect the sensor wire plug to the mating plug of the wire harness until the lock clicks into place.

12

Lower the Blazer and close the hood.

The oxygen (O2) sensors on an Oldsmobile Aurora are a series of small sensors placed in the exhaust system that monitor the amount of unburned oxygen in the exhaust. The O2 sensors relay this information to the engines computer so it can make adjustments to help the engine to run more efficiently and lower vehicle emissions. The Aurora is equipped with four O2 sensors, one in each exhaust manifold, one between the exhaust manifold and catalytic converter, and one after the catalytic converter. You can use a diagnostic code scanner to determine which sensor is malfunctioning. If you do not own a code scanner, take your Aurora to an auto parts store; many have code scanners and will check your car for free.

Instructions

1

Disconnect the ground cable from the negative battery terminal by loosening the retaining bolt and pulling the clamp off the negative terminal. Secure the ground cable so that it cannot accidentally contact the negative battery terminal.

2

Raise the vehicle and support it with jack stands underneath the frame.

3

Disconnect the wiring harness from the sensor. Follow the wires connected to the sensor until you find a plastic wiring connector. Separate the wiring harness by pulling the connector apart.

4

Use a wrench to remove the sensor from the exhaust pipe or manifold.

5

Thread the new O2 sensor into the exhaust pipe or manifold, and tighten it.

6

Connect the wiring harness on the new O2 sensor to the plastic wiring connector that you removed from the old O2 sensor.

7

Lower the vehicle.

8

Reconnect the ground cable to the negative battery terminal. Tighten the retaining bolt that secures the ground cable to the negative battery terminal.

The 1997 Hyundai Accent oxygen sensor threads into the exhaust manifold beneath the heat deflector under the car. The O2 sensor regulates the fuel consumption of the engine based upon the oxygen saturation of the exhaust. If the gas mileage in your car has inexplicably decreased substantially and the check engine light is on, you may have a failing O2 sensor. Buy a replacement sensor at an auto parts store or Hyundai dealership.

Instructions

1

Raise the Accent with a jack. Rest the car on a set of jack stands.

2

Disconnect the wiring harness from the O2 sensor just beneath the exhaust manifold heat deflector.

3

Remove the bolts on the outer edge of the heat deflector with a socket and ratchet. Set the heat deflector and bolts aside in a safe location. Remove the O2 sensor with an O2 sensor socket and ratchet.

4

Install the new sensor by hand to avoid cross threading it. Tighten the sensor with an oxygen sensor socket and ratchet. Reconnect the wiring harness on the O2 sensor by pressing it into place.

5

Replace the heat deflector. Secure the deflector with the bolts and tighten the bolts with a socket and ratchet.

6

Raise the car slightly with a jack and remove the jack stands. Lower the car to the ground.

A knock sensor is a piezometric crystal that advances or retards the engine based on load. Knock sensors are typically located on the intake side of the Ford 5.4-liter engine. All knock sensors connect to an electrical wiring harness and links to the vehicles On Board Computer (OBC). A knock sensors fails like a light bulb fails -- it simply wears out. When a knock sensor does fail, the OBC will automatically retard the engine to minimal fuel efficiency and put the engine in limp mode. The check engine light is a symptom of knock sensor failure.

Instructions

1

Disconnect the negative terminal from the vehicles battery using the 10- to 12-mm box wrench to prevent short-circuiting while changing out the knock sensor.

2

Disconnect the electrical wiring harness from the knock sensor by pulling it apart manually or using long-handled needle-nose pliers. This action is similar to pulling a plug out of an electrical wall socket.

3

Remove the knock sensor by attaching the wobble or swivel bit to the end of the 3/8-inch extension and fastening it to the socket that fits. Insert the socket over the knock sensor. You need the wobble or swivel bit at the end of the extension to access the sensor due to the configuration of the intake manifold.

4

Connect the ratchet to the end of the 3/8-inch extension that is attached to the wobble or swivel bit and the socket. Use the ratchet to loosen the sensor from the engine block by turning it gently to the left. Remove the defective sensor from the socket and place the defective sensor on the work bench.

5

Add a dab of white lithium grease to the male end of the electrical connections of the new knock sensor to prevent corrosion build up and to make insertion easier.

6

Use the socket with the extension to manually screw the new knock sensor to the engine block to avoid cross-threading. Cross-threading occurs when the threads of the sensor do not match up with the threads of the engine block.

7

Reattach the electrical harness to the sensor and reconnect the negative terminal of the battery.

When the speed sensor on a 1999 Chevrolet Silverado begins to fail, the first noticeable sign may be a fluctuating speedometer. The speedometers needle may jump from one speed to another, or fall to zero and then suddenly return to the correct speed. The vehicle speed sensor, or VSS, is the sensor responsible for relaying the vehicles speed to the engine computer. In addition to using data from the VSS to calculate the vehicles speed, it also uses this data to make other computational decisions, including when to shift the transmission. The VSS is located on the tailshaft of the transmission or on transfer case in four wheel drive models. The sensor itself is a magnetic inductive sensor that monitors the magnetic field around a notched, reluctor wheel affixed to the tailshaft. The notches in this wheel interfere with the sensors magnetic field and the engine computer calculates the frequency of this interference and converts it into a speed value.

Instructions

1

Turn off the engine, but leave the ignition on. Connect a scan tool to the Silverados scan tool terminal.

2

Navigate to the live data menu and select VSS. Test drive the vehicle in a safe, controlled area such as an empty parking lot where there is no possibility of hitting other cars or objects.

3

Look down at the scan tools display and note the speed value for the VSS. It should reflect the vehicles current speed. If the speed displayed is 0 or different from the speedometer reading, its likely there is a problem with the VSS or the VSS harness connector.

4

Note the voltage value for the VSS on the scan tool. This value should be listed below or above the VSS speed value. It should read between 1.5 and 12 volts. If the value is outside this range, the VSS is either not receiving the proper voltage or is faulty.

5

Raise the vehicle with an automotive jack and support it with jack stands. Locate the VSS on the tailshaft of the transmission of transfer case for vehicles equipped with four wheel drive. Disconnect the VSSs electrical connector.

6

Turn the ignition on and probe the light blue wire on the connector with a digital multimeter set to DC volts. The multimeter should show between 1.5 and 12 volts. Connect a test lamp to a positive voltage source and probe the black, ground wire on the VSS connector. The test lamp should illuminate if the ground properly connected. If the ground is OK and you find voltage at the connector, then the VSS is faulty and needs to be replaced.

The oxygen sensors on a 2002 Dodge Ram 4.7-liter engine regulate the amount of oxygen burned in the engine, and they improve fuel efficiency and reduce pollution. Over time, the Rams sensors can become ineffective, causing the Dodge to have poor fuel economy and produce excess pollution. The 2002 Dodge Ram 4.7-liter engine has two oxygen sensors, and replacing them when necessary can make your truck more fuel-efficient.

Instructions

1

Locate the Rams oxygen sensors. They are located on either side of the catalytic converter on the exhaust system, and they look similar to a spark plug with an electrical wire at the end.

2

Remove the Rams wiring harness. Pull off the wire at the end of the pickups oxygen sensors. Do not damage the end of the wire harness.

3

Remove the Rams oxygen sensors from the exhaust system, using an oxygen sensor wrench.

4

Apply anti-seize compound to the threads of the oxygen sensors and the threads into which they connect.

5

Insert the new oxygen sensors, using a wrench to tighten them onto the Rams exhaust system. Reconnect the wiring harness to the oxygen sensors by pressing firmly until they click into place.

The Hyundai Elantra has been around since 1991, but wasnt made available in North America or Europe until 1993. Featuring different four-cylinder engines throughout its generational redesigns, replacing the oxygen sensors has remained a fairly standardized repair for the imported car. The upstream sensor is in the manifold or front head pipe and the downstream sensor is near the catalytic converter. The same tools can be used to replace either one, but the sensors are slightly different part numbers and are not interchangeable.

Instructions

1

Start the Hyundai Elantra for five minutes or so to warm up the exhaust. Drive it up onto the car ramps, apply the parking brake, shut the car off and then block one of the rear wheels with a wheel block. If youre replacing the front oxygen sensor, release the hood latch before getting out of the Elantra and then open the hood after setting the wheel block.

2

Crawl under the Elantra with the tools and replacement sensor(s). Locate the sensor in question; front upstream sensor near the manifold and downstream sensor near the catalytic converter.

3

Apply a generous amount of penetrating oil to the area where the threads of the sensor connect to the pipe or manifold. Allow five to 10 minutes for it to soak in. Apply a second coat if necessary.

4

Disconnect the oxygen sensor wire from the wire harness plug connection. A small straightedge screwdriver may help release the press-in tabs of the plug, but be careful since its made of plastic.

5

Use the swivel-head ratchet and oxygen sensor socket to remove the front sensor or a 22 mm wrench for the downstream sensor. Be sure the wire of the sensor is placed in the slot of the oxygen sensor socket. For the 22 mm box-end wrench, feed the wire through the wrench first and then place the box-end side onto the hexagonal shaped sensor. Apply steady pressure on the ratchet or wrench in the counterclockwise position to unscrew it from the exhaust system.

6

Screw the new sensor into the oxygen sensor port. Most all Bosch direct fit sensors have a light coating of anti-seize compound on the thread to make removal of the sensor for the next replacement easier. Do not to allow the anti-seize compound to contaminate the thimble-shaped tip of the sensor.

7

Tighten the sensor until it feels snug. Do not over-tighten as the threads of the sensor are delicate and you can easily strip them. Plug the sensor wire back into the wire harness.

Your Toyota Land Cruiser monitors the oxygen levels in the exhaust using oxygen sensors. When an oxygen sensor fails, your truck begins to burn more fuel, running rich. Your gas mileage will decrease and the check engine light may come on. A Toyota Land Cruiser has as many as four oxygen sensors if it is equipped with dual exhaust. A single exhaust truck will have two sensors.

Instructions

1

Identify the sensor you need to replace. For trucks with single exhaust pipes, you will find the sensors in front of and behind the catalytic converter. If you have dual exhaust, you will have a set of two sensors on each exhaust pipe. Replace them all for ease of maintenance if you can. You can buy sensors at a Toyota dealer or auto parts specialty store.

2

Pull the wiring harness from the top of the sensor. The wiring harness clips into place and will pull free easily.

3

Remove the sensor from the exhaust pipe. You may find two retaining nuts securing it, or it may thread into the pipe. Use a closed-end wrench to remove the nuts if needed. Use an oxygen sensor socket and ratchet to remove the sensor if it threads into the pipe.

4

Replace the sensor with a new one, threading it in by hand and then tightening it with the oxygen sensor socket and ratchet. If retaining nuts secure your sensor, replace them and tighten them with a closed-end wrench.

5

Insert the wiring harness connector to the top of the oxygen sensor. Press the connector in until it is secure. Repeat the process on the remaining sensors.

The oxygen sensors in the 2000 Hyundai Sonata GLS are threaded into the exhaust manifold and the exhaust pipe near the catalytic converter. When an oxygen sensor malfunctions, your car will burn a significant amount of additional fuel. To save the unnecessary fuel expense and possible long-term engine damage, you should replace the sensors as soon as possible. Buy sensors for your Sonata from an auto-parts store or Hyundai dealer.

Instructions

1

Raise the Sonata with a jack. Rest the car on jack stands for stability.

2

Locate the oxygen sensor either on the manifold or near the catalytic converter, depending on which one you need to change. Pull the wiring connection apart. Remove the oxygen sensor using a wrench.

3

Coat the threads of the sensor with anti-seize. Select an anti-seize compound designed for electrical components. Insert the new sensor by hand. Torque it to 40 foot-pounds with your torque wrench.

4

Push the two ends of the wiring harness together. The connector will click when it is attached. Repeat the replacement process on the second oxygen sensor if necessary. Lift the car slightly and pull the jack stands out of place. Lower the car to the ground.

In 1993, Jeep upped the ante in the SUV market by releasing the Grand Cherokee, a more luxurious mid-sized SUV. The 2002 Grand Cherokee came standard with a 195-horsepower, 4.0-liter in-line six-cylinder engine. Being an in-line-six engine, federal emission regulations require just two oxygen sensors, one upstream and one downstream. Replacing the two oxygen sensors in a federal emission-compliant 2002 Jeep Grand Cherokee is a straightforward process, but it may require additional heat for those hard-to-remove sensors.

Instructions

Upstream Sensor Removal Bank 1, Sensor 1

1

Park the Grand Cherokee on a flat surface and allow it to sit until the engine is completely cool. Allow the vehicle to sit for an additional hour to let the exhaust pipes cool.

2

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

3

Crawl under the front of the Jeep until you have a good view of the bottom of the down pipe the pipe that bolts to the exhaust manifold. Find the upstream oxygen sensor screwed into the bottom of the exhaust manifold, near the front of the transmission.

4

Trace the sensors wiring until you reach where its harness connects to the Grand Cherokees harness. Unplug the oxygen sensors wiring harness from the Grand Cherokees wiring harness.

5

Unscrew the oxygen sensor from the exhaust down pipe, using a ratchet and oxygen sensor socket. If the sensor is seized, heat its base with a propane torch, then loosen it. Once the sensor cools, unscrew the sensor from the pipe.

Upstream Sensor Installation Bank 1, Sensor 1

6

Thread the new oxygen sensor into the down pipe by hand, then tighten it to 22 foot-pounds with a torque wrench and socket.

7

Connect the oxygen sensors wiring harness to the Grand Cherokees harness.

8

Raise the SUV off the jack stands and remove the stands. Lower the vehicle to the ground.

Downstream Sensor Removal Bank 1, Sensor 2

9

Lift the front of the Grand Cherokee off the ground with a floor jack and position jack stands under its frame rails. Lower the vehicle onto the jack stands.

10

Position yourself under the vehicle, just behind the transmission and toward the passengers side. Find the catalytic converter, the muffler-like component attached to the exhaust pipe. Find the downstream oxygen sensor, which screws into the exhaust pipe right after the catalytic converter.

11

Trace the downstream oxygen sensors wiring upward until you find where it connects to the Grand Cherokees wiring harness. Unplug the oxygen sensors wiring harness from the Grand Cherokees harness.

12

Remove the oxygen sensor by unscrewing it from the exhaust pipe, using a ratchet and oxygen sensor socket. If the sensor is seized, heat its base with a propane torch, then loosen it. Allow the sensor to sit until it is cool, then continue removing it.

Downstream Sensor Installation Bank 1, Sensor 2

13

Thread the new oxygen sensor into the exhaust pipe by hand, then tighten it to 22 foot-pounds with a torque wrench and oxygen sensor socket.

14

Connect the oxygen sensors wiring harness to the Grand Cherokees wiring harness.

15

Lift the SUV off of the jack stands and remove the stands. Lower the vehicle to the ground.

The 745i is BMWs flagship sedan, carrying the most technologically advanced computer system that BMW has to offer. The 745i, like many other BMW vehicles, contains a vast network of sensors and computers that continually monitor the performance of various vehicle systems. The airbag system in a 745i is no exception to this rule, and has a dedicated standalone computer designed to operate and monitor the airbag system. When this computer detects a fault with the airbag sensor, it writes a trouble code to its memory and alerts the driver by turning on the Service Airbag light. Sometimes this light is illuminated due to a momentary fault with the airbag sensor. In this situation, the light and sensor can simply be reset be clearing the trouble codes from the airbag computers memory.

Instructions

1

Leave the ignition in the ON position with the engine off.

2

Connect the data cable of an airbag-capable scan tool to the communications port on the 745i, mounted underneath the dashboard on the left side of the vehicle.

3

Enter any information that the scan tools asks for such as the year, make, model, engine size, and trim level of your vehicle.

4

Use the menu keys on the scan tool to go to the airbag menu. Select the option to clear the airbag computers memory and wait for the confirmation message from the scan tool stating that the memory is clear.

5

Turn on the engine and make sure that the air bag light is off.