Oxygen Sensors

Generally there are two oxygen sensors for each cylinder head on all later model vehicles (some early models may only have one). Each upstream oxygen sensor is located directly below the exhaust manifold flanges and above the upstream catalyctic converter. Each downstream oxygen sensor is located in the exhaust pipe, directly behind the upstream catalyst, and ahead of the main catalyst. NOTE: Some very early models may only have one catalyst. The electrical connector for the right downstream oxygen sensor is located on the right side of the transmission. - Mazda Pickups Repair Manual == Try Removing the front tires behind plastic shielding to get to the sensors on the upstream O2 sensors and there should be another downstream "easier".

After the catalytic converter (AKA downstream).

I just changed it (the front O2 sensor) on my 2003 Miata. I believe yours will be the same. First, you will need an O2 sensor wrench (about $10 from Advance Auto Parts). Don't waste your time trying to remove it without one. Then follow these steps:

1. Warm the engine, and let it cool to the point you can safely touch the sensor and exhaust pipe.
2. Jack up drivers side front wheel, and put a jack stand under the frame.
3. Remove wheel. (I put the wheel with a piece of 2 x 6 on top of it to the rear of the jack point for added safety.)
4. Apply Liquid Wrench or equivalent to the sensor-exhaust connection - wait at least five minutes.
5. You may still need to add a piece of pipe (or 1/2" spark plug socket with 8" extension worked for me) to your 3/8" ratchet wrench handle to get enough leverage to break the sensor free.
6. If you replace with a universal type O2 sensor (I used a Bosch 15733 sensor from Amazon at $45.41), you will need to reuse your old electrical connector by splicing it in. The Bosch unit I used has a special connector assembly for doing this. It is a bit tedious to assemble but seems very solid. Just follow the instructions. With the Bosch sensor, the two white and two black wires individually (two connections) go together and the remaining the single black and blue and single grey and white wires connect.
7. Reassemble.

You will need to remove the positive battery terminal to clear the check engine light.

they should both be on your exaust

A catalytic converter overheats due to an excess of unburned hydrocarbons reaching it through the exhaust stream for an extended period of time. This overworks the catalyst bed inside the converter, which then starts to become plugged, generating even more heat as it does. In short order, the converter will become a significant exhaust obstruction, causing the engine to overheat and lose power. Eventually, this will prevent the engine from running, due to the inability of the exhaust to escape, denying the engine the opportunity to "breathe"...

They are in the exhaust system. Some have them before and after the catalyic converter.

It is screwed into the exhaust manifold.
between the fire wall and the motor it will be on the muffler...

You need to have the ECU scanned with an OBD2 scanner and retrieve the code that has been set. The code will tell you what part of the emissions system is being effected. This will help you diagnose the problem. Or you can keep spending money throwing parts at the problem until you may or may not find the faulty part.

Rear of engine, upper part of exhaust system.

ONly one that I know of. It is located on the exhaust manifold. hope it helps, duboff

A catalytic converter- (cat-con) takes raw engine exhaust (CO, unburnt fuel, nitrogen oxide) which are very harmful to the air we breathe. (nitro oxide causes acid rain) It catalyzes (splits) the molecules into water vapor, and CO2. CO2 is still harmful to the environment, but not as much as the acidic nitrogen oxide. The water vapor being produced is what makes the steam come out of your exhaust pipe on cold days. Catalytic converters are very helpful (and lawfully required) to the environment. The only problem is that they need to warm up from exhaust heat before they begin to catalyze the exhaust. So about the first 10 minutes of driving are the most harmful ones. And for the last downside of cat-cons, they are made of Earth's most precious metal, platinum. That is why they are so expensive.

When an oxygen sensor goes bad a car will burn gas at a higher than normal rate because it will not be producing as much power as before. The oxygen sensor checks the amount of exhaust.

it is located right below the exaust manifold flanges above the catalitic converter

a 1996 deville has a total of 02 sensors. the 1st on is located on the bottom right side of the engine. The second is lower left side on maifold pipe,(left side of engine. The third one is before the cattalytic converter(bottom of car) And finally the fouth one is after the cattalytic converter,(follow the 3rd one back). All require special tool to remove. Sensors 1,3,4, are the simple to replace. Sensor two is in a tight spot. It almost took me an hour to replace it. All others take no more than ten minutes to replace. Good luck

on the y piep down clos to the cad converter Under the truck and they screw into the headers. You will see 2 wires coming from each sensor

As with any vehicle equipped with one, a bad O2 sensor can cause the onboard computer to change the amount of fuel sent to the cylinders and cause the engine to run too rich or too lean. Either way, poor performance/poor fuel economy will result and in extreme cases the car can stall, not start at all or otherwise be rendered undriveable. It's a screw-in part with an electrical connector found near where the exhaust pipe is bolted to the exhaust manifold. Penetrating oil and patience is advised, but a shade-tree mechanic can replace it fairly easily. They aren't that expensive.

Check Engine light is on. Engine OK when cold, but when reaches operating temperature it stalls at idle.

IN THE EXHAUST SYTEM meaning a 4 cylinder has 2 a v6 has 4. IN THE EXHAUST SYTEM meaning a 4 cylinder has 2 a v6 has 4.

If the check engine light is on, something may be unplugged. The converter might be too small for the car, or may have been damaged during install... change the fuel filter check the fuel pressure d

there are two one on the intake manifold (facing radiator) and the other one on the exhaust pipe underneath the car

The oxygen content of air remains constant at around 21% regardless of temperature. However, at lower temperatures, air becomes denser, which can affect oxygen delivery to the lungs during respiration.

First you have to loosen the front wheel on the passenger side of the car. Then you jack it up, put it on jack stand and remove the wheel. Next, you have to remove the plastic shield from the wheel well. After you do this, you have to remove the crank pulley, and timing cover from the car. Next you remove the timing belt and they you'll have access to the crank seal. Not really too bad of a job. Just be careful removing the seal making sure you don't nick the crank. You can take a small drill bit and drill a hole at 3:00 and 9:00 position and screw in a couple of sheet metal screws. Then, take a pair of vise grips and in an alternating pattern, pull on each side until it comes out. If you decide to use a small screw driver to pry it out instead, cover the tip with duct tape to make sure you don't scratch that crank. After you get it out, put a light coat of oil on the outside of the new seal and use a large deep well socket the same size of the seal to GENTLY tap it back in. This job took me about two hours to do. Since it appears you've never done it before and you don't want to rush it, plan on five or six.