[jfjohn]

96 taurus gl. Got p0141, bank 1 sensor 2. Which is bank 1? Sensor 2 is after that cat, right? thanks.

[jfjohn]

How hard is it to replace this sensor? It looks like the harness plugs in near the top of the steering rack where other wires plug into the rack. Do you unplug it by reaching down from the top or from the bottom? Is there interference? Does anything have to be removed in order to unplug the sensor from the harness? Thanks.

[Poppy]

bank one is the firewall side of the engine.
sensor two is the one after the cat.

[jfjohn]

Originally Posted by Poppy

bank one is the firewall side of the engine. sensor two is the one after the cat.

thanks, Poppy. How do you reach the connector on that one? From above, below, or maybe through the wheel well?

[Canuck623]

Really it's whatever works for you. For me I do them from under the car. My forearm is a little too big to go down from the top. The connector will pop out of the clip and it will pull far enough to make it easy.

[jfjohn]

Originally Posted by Canuck623

Really it's whatever works for you. For me I do them from under the car. My forearm is a little too big to go down from the top. The connector will pop out of the clip and it will pull far enough to make it easy.

Canuck, do you actually reach up and pull the connector from the clip with your hand or do you pry it out of the clip with a screwdriver and let it drop? Are you able to get it back in the clip when you install the new sensor? I haven't gotten under there yet but it looks tight.

[phantom]

I take a narrow screw driver to push the tab in and pull the hard shell(blue part)

[jfjohn]

Is gas mileage affected when sensor 2 goes bad? It's too bad sensor 1 and 2 aren't the same. I have an extra sensor for sensor 1 but I guess it won't work in sensor 2 location. Also do you remove the sensor by first warming up the car so the pipe isn't cold when you take it out? Do you put wd40 on it too before taking it out? Sensor 1 came out easy last time. I hope sensor 2 will the same.

[Canuck623]

Hi sorry I am a little late getting back to you. Yes you can pop the connector out of the bracket and it should go back in too. It is tight but once down there it isn't as bad as it looks from the top. Depends om where you live. If you are in the rust belt yes to all of the above and a prayer or two wouldn't hurt either. If you are in the desert like I am they just unscrew like they were new.

[jfjohn]

So with a p0141, what do you think the chance is that it actually is a bad sensor and not a bad wire in the harness or pcm?

[Canuck623]

There are tests for that. You need to get a diag tree for that code and go through them and that will tell you whether it is wires or sensor. In my many years of doing this I have yet to see a PCM cause the code. Inspect the wires for damage. Look very carefully for any type of rodent damage. Rabbits, rats and squirrels love to eat wires.

I left part of your question unanswered from before too. Yes the sensors can have a negative impact on fuel mileage.

[jfjohn]

Thanks everyone for the replies. Is there a oxygen sensor relay that could be bad causing this or is there not one on this car?

[jfjohn]

What brand O2 sensor would you get? Is bosch ok?

[Canuck623]

Bosch is ok. Not as good as OE but better than most aftermarket stuff. There are no relays of any type for the O2's. The reason I like OE is the plug fits properly. With the bosch the alignment lugs are removed so they only need 1 style for all applications. It is easy to plug the wrong O2 ito the wrong harness plug.

[jfjohn]

Thanks, Canuck. What do you think about Denso brand sensors?

[jfjohn]

Well, I think I fixed it. I got under the car and got my fingers on the connector for the 02 sensor and found that it looked like it was plugged in but wasn't! I'm wondering if the mechanic had to undo it when they replaced the rack and forgot to replug it in but why would it appear plugged in but not all the way in? It came apart just by lightly touching it. I couldn't plug it back in from underneath so I took the snorkul tube off from the intake manifold to air filter box so I'd have room. I still couldn't reconnect it from reaching down so I used a screw driver to pop it out of the clip. It wouldn't drop down far enough to get it from the bottom so I pulled the 02 sensor up, a little further over to the passenger side of the car and then was able to reposition it so I could push the two connectors together and heard the clip snap in. I couldn't get the connector to mount back onto the plastic holder so it's kind of just hanging loose but it really can't go far so I'm going to just let it hang there. I reset the code so we'll see if it comes back on.

[Canuck623]

I would give that a 100% chance that it was left unplugged by the tech. You should be good to go. Oh and no, I do not like Denso. They fail prematurely in my experience.

[jfjohn]

Thanks, Canuck. So far, so good. No SES light. Does that sensor after the cat affect driveability? Does it affect fuel mileage or does it just report cat performance? I guess what I'm asking is does the computer make any engine adjustments based on what sensor 2 reports?

[Canuck623]

It reports the cat performance but can also have an effect on fuel mileage because the PCM will try making adjustments to compensate. Once the PCM reaches it's preset parameters and it can't adjust anymore then it flags the fault as a bad cat. With it unplugged there is no monitor for the PCM read. It would have a hard fault to deal with and would just pick a setting for the fuel in that bank and ignore the other 02 instructions.

[jfjohn]

Thanks, Canuck. Both of my sensors after the cat are original, 15 years old with 175k miles. Could they be messing up my gas mileage being that they are so old or do I only have to change them when I get a SES light?