Aug 14, 2007

Changing the O2 Sensor on a 1996 Saturn SL

Left: The oxygen sensor screws into the exhaust manifold

I sometimes use this website to post mechanical information, as I am very much a fan of the concept of shared knowledge. Those who do not wish to be bored with auto repair, please continue on to the next post.

My 1996 Saturn SL has had some stalling and idling problems that have gradually worsened in the last few months. I used my philosophy of "repairing the least expensive related parts," and changed the spark plugs, plug wires, and fuel filter, but the problems continued.

I moved next to the oxygen sensor, which is also known as the O2 sensor. After replacing this sensor - which measures the concentration of oxygen remaining in exhaust gas to improve the efficiency of the combustion process - my car no longer stalled and the rough idle disappeared.

Left: the used oxygen sensor after removal from the manifold

The process of removing an O2 sensor is quite simple, and I suspect that one could continue wearing one's flashy Air Jordan shoes whilst changing said part. Here are the steps you can follow to replace an oxygen sensor:

1. If you have a twin-cam engine (it will say so on a big label on the valve cover), you will need to make sure to purchase the correct sensor. There is also an oxygen sensor that screws into the exhaust system near the catalytic converter, but this is usually a special-order part. The front oxygen sensor that screws into the manifold is typically the first of the two sensors to wear out. Most auto stores stock this oxygen sensor.

2. Allow the engine to cool. It is best to change this sensor in the morning after the engine has cooled overnight.

3. The auto parts store will try to sell you a special O2 sensor wrench, but you can remove the old oxygen sensor with either a box wrench or an adjustable wrench. Just be sure to disconnect the wiring first and do not over-torque the wrench, or you will end up snapping off the sensor in the manifold (very bad). The wiring on the O2 sensor usually clips into a connection, and you have to depress the plastic tab to connect/disconnect the wiring.

4. Apply a light amount of grease on the threads of the new sensor, making sure to wipe off the excess. This will prevent the sensor from rusting or becoming corroded to the manifold.

5. Screw the new sensor into the manifold. If you do not have a torque wrench, go no more than a quarter-turn past hand tight. Again, you do not want to strip out the new sensor in your manifold and have to re-tap it.

6. Reconnect the electrical wire to the assembly.

7. Fire up the engine and see if you now have a fine running automobile. If not, curse the $60 you spent on an oxygen sensor and restart the diagnosis process. Hint - you might next want to check your MAP sensor.


Man with the Muck-rake said...

You saved yourself [and perhaps another blogger] a few hundred dollars. My sensor years ago cost me about $300 at the dealer.

Yikes! Never again.

KC Baltz said...

Thanks for documenting this. I had the same success with this operation this morning and it was exactly as you described. I'll add that the store offered two sensors, an OEM and a "Generic". The generic is much cheaper ($20 vs $65), but I chose not to go with it as doesn't come with the right plug; you have to solder the old one on.

me!!! said...

Thank Gog you Blog! My Saturn is failing smog, the bank 1 O2 is out and they think the CAT converter as well, - well, now I know where that O2 is I'll replace it and see if it doesn't save me the $300 to replace the CAt too..

Thanks again!

Anonymous said...

You apply only anti-seize to the threads of any new O2 sensor. Some sensors companies are applying it in the manufacturing process, so you don't need to apply anything else. Applying anything other than anti-seize or getting any on the sensor tip will ruin it. I have been a GM technician for 30 years and installed at least 1,000 in my lifetime. So, don't let anyone tell you different.

Anonymous said...

Hi i have a saturn that looks like it is the same motor. I have a 2000sl2. I need to replace my map sensor and i cannot find it. My husband just left for Iraq and i have no other way of fixing it, i have to do it myself. I have already bought the part and i was told it was an easy fix but i cant find it in my car. Any help would be great. Thank you

RULE said...

This is really great blog for O2 Sensor. I have one related to OXYGEN SENSOR PARTS!

Anonymous said...

I have a 1996 Saturn SL2 with 120K miles. Got a Service Engine Soon Light. Went to Autozone and checked the OBD code was P0133. This blog helped me to understand how simple the changine the O2 sensor will be.

Anonymous said...

thanks not much of a car person so when i got the diagnostic test back i was kinda of like uhhh?..this saved me a trip to a garage =]

Matt said...

Hey there. I know this blog is old, but I figured I would say a way of thanks. I took mine to Midas this morning and they wanted to charge me $200 just for changing that one. A Google search or 2 later and here I am. :) Way better (and easier) than the $1300 they were wanting to charge me!

Anonymous said...

every time the check engine light comes on it indicates O2 sensor.
by the time i buy one, the light
goes out. i thought they either
worked or not. now am not sure if i should replace it. however, your blog is great information.

Curt said...

Worked like a charm. Has to be the 3rd time it went bad and I wish I knew it was this easy years ago. 235k and still going good for a 16 year old car.

Teresa Phelan said...

Thanks for the info....I have a Saturn sl2 1996......idling really high driving hard.check engine light has been in fir months put on machine saying I need crankshaft????? Doesn't exist now I need this but I read ur blog which has me believing this can be fixed thanks again