Okay, so this is starting to bug me... I've checked out the parts diagrams and am a bit confused.

 

Would anyone mind taking a quick pic of their O2 sensor (rear) and posting it? I am having a troubling time locating mine. Also, any easy way to trace the wiring for this? Where does it plug in and where would it join the rest of the harness? Pics would be great...

 

02 OBW 2.5.. so anything 00-04 I would imagine would be pretty close..

 

Very Very Much Appreciated!!

 

Cheers.

Here's the catch: California models are different.

 

I don't have one handy to take a pic of for you, but I'll give a shot at guiding you to it.

 

On 49 state cars (Non-CARB) The o2 sensor is just after the second cat. So you follow your exhaust manifold off the heads, it comes together at the y-pipe; right where the two header pieces join you'll find the front o2 sensor on the top. This sensor screws directly into the front catalytic converter. Continue to follow the exhaust back and it comes to another large bulge (the second converter) The rear o2 sensor is on the top on the drivers side of the converter. It is a 4 wire sensor and the wire will run to the drivers side of the transmission (AT and MT are pretty close to the same spot) The wire then runs over the top of the tranny and to the passenger side of the engine compartment. The top right bell housing bolt of the motor has a bracket on it with three plugs, a brown one, a black one, and a white one. The white one is the rear 02 sensor. It then connects to the main engine harness.

 

Now, on California cars, its a bit different. On the exhaust, the front o2 sensor is in the same spot. On the front catalytic converter, follow it the the rear of the converter, and on the top passenger side (kind of hidden) The rear 02 sensor plugs in. Its all in all about 8" from the front 02 sensor. The wires go directly up the passenger side of the engine and are shrouded with yellow sheilding.

 

Good luck. Let me know if you need any other info.

 

Dan

If you're looking form the top down at the exhaust system next to the transmission. You'll see where the axle comes out of the differential. The front O2 sensor is directly under that.

The rear O2 sensor comes out behind the resonator.

Number 11 is the O2 sensor.

 

Here's the catch: California models are different.

 

Now, on California cars, its a bit different. On the exhaust, the front o2 sensor is in the same spot. On the front catalytic converter, follow it the the rear of the converter, and on the top passenger side (kind of hidden) The rear 02 sensor plugs in. Its all in all about 8" from the front 02 sensor. The wires go directly up the passenger side of the engine and are shrouded with yellow sheilding.

 

Good luck. Let me know if you need any other info.

 

Dan

 

Awesome Dan, that is a huge relief, I completely thought I was going crazy.

 

I always spotted the one sensor on the first cat and assumed it was the front (A/F). Turns out the one in plain view from under the hood was the rear (O2). Found both of them now, as you said, attached to the fore/aft of the first cat. Interesting how that isn't very well depicted in the manuals/parts books. (NJ is a CARB state.)

 

One related question, and this has been brought up in other threads. Is it accurate to say that for at least 00-04, Cali or Fed, the O2 sensor ONLY monitors catalyst efficiency and does not affect fuel trim or anything else?

 

Regardless, thanks again for the help, happy I got this sorted out!!

Edited September 30, 200916 yr by nickb21

The front O2 sensor does a big part in adjusting fuel trim. The rear is only a monitor.

Thanks to all for the help and info, very much appreciated.

 

Wasn't too too much of a pain, but I learned a few things.

 

Cheers.