Where are the darn O2 Sensors

[PhantomCougar]

Hello everyone.

First I must introduce myself. I am a newbie to this board, but not to car forums in general. I have had a lot of good help from the forums for my other cars, I'm hoping you guys can be as helpful for my 97 Grand Am SE. And I did search first.

The problem is that I got a check engine light and Trac light off... took it to Autozone and it came back Oxygen Sensor. He didn't specify before or after the Cat and I didn't think to ask.

Anyway, where are these damn things? I found the one before the cat. Its under the cover behind the engine just on the drivers side of the headers. That one I replaced, and the light came back on after a couple miles of driving.

So now I want to replace the one behind the cat. But I can't find it. And I can't find any online documentation telling me where it is.

Also, how many total are there? Are there only 2? One on the headers behind the engine, and another one down the pipes? My Probe had only 2, but my Cougar has 4! So you never know.

Thanks for the help. I really appreciate it.

Reagan

[Matt95GT]

You won't find much accurate diagram information online. If you are going to do any amount of work yourself, I'd highly recommend picking up the GM/Helms service manuals. www.Helminc.com

Correct, the secondary O2 sensor is after the cat... you may need to get the car up on jack stands and get under it to really see it. Also, depending on the code... typically the code for the second O2 sensor indicates that the cat is under the efficiency threshhold meaning the cat itself is the problem, not the sensor.

There are only 2 sensors.
On a sidenote, my mom's 2.5 Duratec (in a Mystique) needed to have all 4 O2 sensors replaced at around 70K... a rather expensive issue. I see that is rather common on that engine too.

[PhantomCougar]

Thanks.

So when you say after the cat... you mean the main Cat. Like toward the back of the car? Or does the LD9 have pre-cats in the headers like the Duratec? If so, where exactly is that other sensor? I was all over that car looking... jacked it up and looked, everything.

And the code came back that the sensor just wasn't responding or something to that effect... not so much under effeciency... so I figure I'll try and replace first... then escalate.


And ooh yeah, the Duratec is a pain. I've got 81,000 miles on it with no problems yet... but at $50 a sensor... its $200 in just parts to replace... and every one of them is damn near impossible to get to.

Thanks again.

Reagan