O2 sensor location

Hi guys,
I have a 1999 tacoma with 2.4L 2Rz-fe engine. I have an engine light on and the code reader tells me that O2 sensor bank1 sensor 1 is the issue. I am a pretty good Googler if that's a word and for about three days I have been unable to locate this sensor's location. There is nothing on the pipe upstream of the cat. I can't find anything on the exhaust manifold either. I'm racking my brain here. Please help if you know what you're talking about. Thank you guys so much in advance.

 

Its gonna be after the cat. Between cat and muffler.

 

Here is a pic of the wife's 1998.

 

Firstly, thank you Kirk for your quick response. Yes, I found that one right away but it was my understanding that the one after the cat and before the muffler was Bank 1 Sensor 2 and that there was another one before the cat (upstream) somewhere between the cat and the header call Bank 1 sensor 1 which is the one that the code reader is finding trouble in. Can you confirm? Thanks again so much.

 

I can't confirm now, left the house.

I did not feel another sensor on the exhaust/ manifold when I was under the track earlier.

Funny, my truck is a 3.4. I know exactly where the sensors are. I just don't get under the wife's truck that much. The fact that she drives it 3000 miles a year probably has a lot to do with that. Lol.

If I get a chance, ill poke around to satisfy my curiosity.

 

Should be on the top side of exhaust right in front of the cat.

 

On the 3.4, yes. Not the case with the 2.7.

 

i was going off of this for the 2.4

 

Correct, on other similar engines there is one right in front of the cat. On this 2.4L there is one behind the cat but there is definitely nothing but pipe all the way to where the pipe meets the manifold flange. ....although there is a shield over the manifold no wires can be seen coming from any of the holes of the shield. I have researched replacement exhaust headers just to see if I can see where the sensor could go and I see nothing. I'm completely baffled. To add to my confusion,

 

http://www.lceperformance.com/Street-Header-Kit-2RZ-1995-2004-50-State-Legal-up-p/1041048.htm

 

Devinzz1, good diagram. That is where I would think it should be. I wonder what year that diagram is for cause there is nothing but pipe in that area. Thanks for all the help guys. I need to figure this out. This is my father in law's only means of transportation.

 

https://www.youtube.com/watch?v=QPZJyHT5mGk

3:23 in this video it can be seen.

can you take some pics of your exhaust?

 

Let me see if it come out at night.

 

This is take from around the exhaust manifold flange area down.

 

This is taken from the cat towards the front.

 

thats not factory. this thing might not have an upstream o2 at all..?? must not run very good and be a pig on gas.

 

See, nothing but pipe.
I just bought this truck for my father in law a few days ago. The previous owner sold it to me with the check engine light and assured me that it was the Oxygen sensor. They were not lying cause my code reader confirms it. However, now I'm thinking that someone has removed the oxygen sensor all together and added just a straight pipe with no hole for it. Why? Could there be something else wrong and they did this as a quick fix in order to not have to fix something else? ...Or to mask other symptoms?

 

Devin, it did have a little hesitation on exceleration but I just figured it was the bad sensor. So what do you guys think? A new section of pipe with the sensor bung in it should fix it? I gotta see what they've done with the truck side of the electrical connection. Hopefully it's still there somewhere.

 

its possible it was rusted out around the bung and they cut section out and added this in. why without the o2 i wouldnt be able to tell you... the plug for o2 should route up over the trans.

 

Devin, you were right. I just found the plug still connected and cut on the sensor side laying on top of the trans. Which proves that the sensor should go right in front of the cat just like you said. If you search on eBay "Tacoma 28788" they sell a down pipe that attaches to the header and the front of the cat with the O2 sensor mounting point. ...and it shows to be compatible with all models of that year. I guess, mystery solved. I just hope that reconnecting all this doesn't open up a new can of worms. Can anyone hypothesize why someone would delete an O2 sensor? Thank you all so much for the help with this. You guys rock! I'll post pics of the job once complete.