Cat problem?

kev2

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#31
No TSB's for those codes - a part change for p0174 upstream BUT that in 2005 surely Lexas part stock will have new part, the # remained the same.
I hope this FSM info helps,
 

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infj23

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#32
Yes, the new B2S2 O2 sensor is aftermarket. Manufacturer was Denso.
The other 3 O2 sensors have not been changed by me, so I have no idea if they are original or have been changed. Car now has 372,000 miles. The B2S2 is the only one that has thrown a code.
 

infj23

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#33
No TSB's for those codes - a part change for p0174 upstream BUT that in 2005 surely Lexas part stock will have new part, the # remained the same.
I hope this FSM info helps,
kev2,
Yes, this helps. This diagram shows that I was in the right area on the ECM. I checked for continuity between the O2 connector HT and the yellow wire that goes to pin 33 on the ECM and the circuit showed open (infinite ohms--no electrical connection). Same with looking for continuity between O2 connector OX and pin 29 on the ECM--black wire.

I am no expert here, but it makes sense to my understanding of electricity that I have a short or broken wire between the O2 sensor and the ECM. Could I snip the existing wire and run jumpers from the O2 connector to the ECM? Any chance that would fix this?

If needed, please see my post of 7:19 pm on Sunday past for details on my multi-meter testing of the circuits.

Thanks!
David
 

kev2

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#34
if no continuity run a jumper BEFORE cutting and nicely tucking wire repair..
Did any of the trouble trees mention to check for open often there is a ohm test... But hey its a step in resolving this finally.
A jumper is not inventing the wheel;

I advise toyota/lexas sensors but open circuits wont be solved by that.
If you need more let me know will have to get back to toyota site.... time permitting
 

billr

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#35
Well, I have to admit I haven't been studying this thread carefully. I just jumped in with my comments because it seemed like you were beginning to feel neglected. I see now that in reply #16 the WB and NB cal curves are included.
 

infj23

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#36
Well now I am confused. Perhaps overthinking this, but want to be careful.
The wires going from the O2 sensor (B2S2) are yellow (to pin 33) and black (to pin 29).
According to the schematic provided by kev2 in post 31, the wires coming out the back of the O2 connector should be yellow, black, black/white, and brown (with black and yellow going to the ECM). See attached pic, which has wires that are yellow (I think--it looks white in the pic but I think the flash washed out the yellow), blue, black/white, and brown. So there is no plain black wire that I expected to find to connect to pin 29.
According to the schematic provide by nick2b in post 16, the wires coming out of the connector are numbered 1, 2, 3, 4. Which color is which connector? For the life of me, I think I have the thing oriented correctly, but then I'm not sure. Which way is up?
And which of those wires, by color, should I jumper to pin 33? Which to pin 29?
I want to jumper around these to see if that fixes my problem, but want to be sure I connect the right wires. Seems like it would be a really big problem if I messed this up.
Really appreciate any help. I may be wrong, but have myself convinced the problem is wiring between the sensor and the ECM. But I have myself confused and am second guessing this, so anyone who can make this simple, that will be amazing.
Thanks!
David Lexus ES330 B2S2.jpg
 

billr

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#37
What makes you think "B" means "black" and not "blue"? I hate these modern lazy schematics. The old notations of "BLK", BLU, BRN, etc were hard to mistake.
 

infj23

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#38
Because the color on the schematic is black. The brown looks brown and the yellow looks yellow. If black=blue, then I think I'm good to go.
But, the wire is blue at the connector and black at the ECM.
 
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billr

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#39
What schematic, the one kev2 posted in reply #31. Yeah, it looks black there, but that could be a mistake.

It looks like you have a distinct BRN wire on both sides of the connector and a light-colored one that could be YEL although it looks WHT. On either side, is there a wire that is clearly BLK/WHT (black with white stripe)? Are we only fussing about the fourth wire, that is BLU on both sides? Maybe pictures with the wires spread out would help me see what you have there better. Which connector half is on the harness, the sockets or pins?

PS: This has me confused. It sounds like you are saying a wire changes color from one end to the other...

"But, the wire is blue at the connector and black at the ECM."
 

infj23

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#40
Yes, billr, I am very confused. I appreciate your responses.
I think I may have figured out my problem. If you, or anyone, can answer this for me, I think I will have this figured out: from the connector that the O2 plugs into, the wire colors leaving that connector should be the same colors that arrive at the ECM. Is that right?
After banging my head against the wall, I may have finally discovered that I am my own worst enemy. See the attached pic, particularly the part circled in yellow. See the two bumps on the side of the connector? Compare that with the connector I have been working with: only one bump on the side of the connector.
These connectors, of course, are designed to plug in to the right source only, so they cannot be messed up. Finally seeing the two bumps in the diagram, instead of 1 in the picture, tells me I have been spinning my wheels.
I just went out to the garage and took a quick look at that other connector. It has two bumps. The wire colors seem right; there is a yellow wire and a black wire coming out of it (although I won't guarantee it--lots of grime--I'll clean it off and have a better look tomorrow).
So, is my understanding correct that the wires coming off of this O2 connector should be the same two wire colors that go to the ECM? If so, that tell me a lot (including that I'm no mechanic!) and I now have to start from scratch on figuring out my problem.
Wow, have I made this harder than it needed to be!
Thanks again to all!
David Lexus ES330 O2 connector diagram.jpg
 

billr

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#41
You think maybe you have been testing/changing the wrong sensor?

Yes, wiring in a specific circuit rarely will change color, even if there is an intermediate connector. In this case, the schematics indicate there is no intermediate connector, so a color change for the wire is near-impossible
 

infj23

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#42
Yes, I think that after all of this time and effort (and blood, sweat, and tears) I may have been checking the wrong thing.
Now I'm trying to identify the part number for the Bank 2 Sensor 2 O2 sensor to see if the connector end looks like what I have been working with.
Does Denso 234-4261 look good for Bank 2 Sensor 2 on my 2005 Lexus ES 330?

And, is Bank 2 closer to the front bumper or closer to the windshield. I think bumper is the right answer, but would like confirmation if possible.

Thanks! What a ride!
David
 

billr

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#43
I would think B2 is closer to the windshield (the "rear" bank).

Rock Auto shows that Denso number (234-4261) as being for the front down-stream; what I think is B1S2. 234-4064 is the Denso number for B2S2
 

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#44
Done! Fixed! The ordeal is over!

First, and most important, my profound thanks to all. This post is #44 is a long saga. The length of this, frankly, is my fault. This is me:

dunce.jpg

The punch line here is that my problem was with O2 sensor B2S2 but I was working all along on B1S2. Right pew, wrong church. Both downstream, but I was on the wrong bank the whole time.

When should I have known?
1. Ideally, before I started. I was somehow sure that Bank 2 was on the "back" of the engine, the half closest to the firewall. Not so! That is Bank 1. Bank 2 is closest to the radiator. Thinking back I have no idea how I first got those mixed up, but when I did, it was set in concrete.

2. I should have figured it out when, many posts ago, I reported that unplugging (what I thought was) B2S2 that B1S2 went to zero volts. What really happened, obviously, was that I unplugged B1S2 and, duh, it went to zero volts. That should have been a clue, but not an obvious enough one for me.

3. Finally, I could not make sense out of the wires. Different color wires were leaving the O2 connector than were arriving at the ECM. That still was not enough, although it should have been conclusive proof, but I missed it.

4. When I finally figured it out was going to Rock Auto and looking up part numbers. One of the O2 sensors there was identified as "front" instead of by Bank. Wait! They are calling "front" something I thought was "back." Finally, it hit me. I had the Banks all wrong and what I thought was my problem was really B1S2. I needed the other O2 sensor that was after the cat, which was the one for the code I had been getting all along.

So, after getting a new O2 sensor for B2S2 (Denso mfg), installing it, and buttoning up the car, I took it for a test drive. Smooth as silk, once again. Even, steady, quiet idle. My scanner shows both B1S2 and B2S2 fluctuating properly between 0 and 1 volts. Everything is once again beautiful with my car.

In grateful appreciation, I have thrown a few more nickels on the pile. Thanks to all.

I bought this car with 258K miles on it. Now at 372K. My initial goal was 400K. That is starting to look pretty good. I may have to up my goal soon to shoot for 500K.

The end!
Thanks!
David
 
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