Hi All ~

It has been recommended (here0 that I change my O2 sensor in my '93 SE in order to improve my gas mileage. I have a hard time getting 20MPG under any circumstances, yet I see folks getting almost 30MPG on the highway. I have done a search of the forums and have not come up with much.

So my question is simply: please tell me what I need to know to change the O2 sensor. And if you have the pix, show me your O2 sensors! How does the O2 sensor affect mileage anyway?

In regards to the mileage, I drive the Bonne as though it had a raw egg under the gas pedal. I have recently changed the air filter. The car otherwise runs smoothly. ANy other suggestions for improved economy would be appreciated.

Thanks for your help.

In the back of your engine, look down. You'll see your rear exhaust manifold. You should notice a spark plug looking thingy there. That'* your O2 sensor. There'* a special socket you can use to get it out. Costs about 10-15 bucks.

I don't have any pics available, but that should help.

The O2 Sensor provides input to the ECM in order to adjust fuel trim so that the engine isn't burning too rich or too lean.

Rear exhaust manifold. Yours should be attached to the car.
See the threaded hole above the #4 exhaust port? Just before the downpipe flange at the top of the pic. (yes, I cleaned out the ceramic paint from the threads before installing the new sensor).

You can do it with a wrench. You don't need the special socket. It'* tight, but should take you only 5 minutes.[/img]

AC Delco Sensors ONLY. Part numbers are in Techinfo. You can order it from www.gmpartsdirect.com for a 40% discount from dealer retail.

LMAO

I changed my O2 in a matter of mins. All I used was a rachet, extension bar and crows foot socket. & if I remember correctly I picked up atleast 5-6mpg after if was changed (it was really old & tired.)

Well, I expected a little verbal abuse, and here it is!

Seriously guys, thanks for the help. I'll get out there and find that sensor, though I am sure my manifold isn't fire engine red, and I am pretty sure it'* still attached to the car!

Is this a GM dealership-only part, or can I get it at AutoZone or Advance Auto?

www.gmpartsdirect.com

Cheaper than the dealer. The other places ONLY if they have AC Delco sensors or can get them for you.

Price it through GMPD and figure in shipping to make your choice.

The 98'* have two o2 sensors one on the back side of the motor the other is under the car on the exsaust pipe.Did mine awhile back.I think Advance Auto used to loan out the specal socket to do the one on the back side of the motor. Later .

From the gearhead photobucket.. (Willwren )

If you look behind your motor you will see your O2 sensor.

Yep...I found it! Right where it should be. Just remove the spark plug wire, and wrench it out. Looking at GMparts Direct, the "Oxygen Sensor" I am finding is something else, because it surely doesn't look a thing like this. I found it at a few other places, though. Is GM OEM recommended here, or is there a better brand? And I see 1,2, 3, and 4 wires listed. I am thinking mine is a 1.

Thanks for any feedback. And thanks for the help so far.

John