Cat problem?

nickb2

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#16
The problem may reside in between the o2 connector and ECM. So do in a circuit check from ECM/ECU would help.

So lets focus on the P0157 code you got as the others were pending. I am reading your initial writing correct I assume, as you wrote occasionally you would get a B2S2 code. That sounds like an intermittence fault coming on, but now the pending codes are starting to appear which again leads me to a circuit diagnosis first as throwing a cat here will be useless if the irish green mob hit a connector or a pinch wire or ground choke point. .

Here is a chart to diagnose that code and the 2198. Remember I said that lexus calls to check all other codes first prior to the P2A03? The P0174 is just a symptom related code relating to the 157 (b2s2) and 2198 (b2s1). Or possibly a vac related trouble, air induction related to that bank etc. But we do need to focus on that side.

So here are charts for both those codes. Again, neither of those codes call for a defective cat at this time. All pertain to either a circuit or defective sensor or as I wrote above, something else such as injector/s etc. I will try comparing wiring from both charts to see if there may be a common ground that may affect both sensors of this bank 2.

It may take me some time to post back as I do have a life outside work and this site. Such as making a chinese buffet for my GF and should get cracking in the kitchen. In the meantime, here are those charts in pdf. Maybe someone else can study them also and give valid thoughts there.

But I do still think this is a circuit issue. And god forbid, maybe a faulty PCM. But that is as I say often, the last thing to suspect. But it is on occasion what happens.

BTW, what's on the menu? Fried rice with scrambled eggs and green peas (home made), wonton soup (store bought), chow mien (home made), soy sauce and brown sugar with a hint of maple syrup, spare ribs (home made). I left dessert up to her. Just bought a new kinect game. UFC. Should be funny to see her trying to do a rear naked choke. I will probably choke on my beer.

Without further ado, here are those two PDF's.
 

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infj23

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#17
Hey Nickb2,
Thanks so much for the reply. Weather was nasty here--cold and wet--so I decided not to pretend to be a mechanic today. I'll get on it next time I get a chance and have decent weather.
Hope your dinner with the GF turned out well. I think she is lucky to have you!
David
 

nickb2

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#19
She has been by my side for a few years now. We once stayed together under one roof/my roof. Things got bizarre.

But ever since she found the right her place. Equilibrium. :cool:
 

nickb2

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#20
BTW, chinese stuff ended up in the back of the freezer. I call out for dinner. some shitaourk stuff. It was good. But my GF was not impressed.

I know I said I wouldn't say anything stupid. So I will try to keep my ocd to a level. Not that I suffer from that. But, I must say, does anyone here date a greek woman?


Not easy women when they want to take control of your kitchen. I almost had to call rape while she was molesting my syte. The "food" goes way high up on totem pole before hanky panky. Some times I think to myself. Am I that lucky?

After a week apart from her, I still find her annoying. But that comforting annoying. Such as, did you bring you bank card? No. She well you need that (in a high pitched voice that reminds me of old Archie bunker tv show). I say I got bills in my pocket, what do I need my cash card for?

This is where I go ballistic. Can't you go out and drive the car for once? Like fill the damn thing off, or maybe once in a wet dream, it might be you dropping ME off at work. Did I buy you that rust free red echo? That thing will run on diesel if you want it to.

But she just want s it for a visual. Thing hasn't moved. Only time I moved it was when she said she needed winter tires. I asked why? Now?

She said in case I want to drive. I said ok. lets see how far this goes.
 

nickb2

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#21
I find 4 Swedish tires. This is a steal. I scoop them up for 10$ a tire. 12/32 new kind of used. Slick new out of van those measure 13, no more. But they work great for quebec.

But I am doing again what I do.



Set of tires, 40$. Then I go score the local guy down where they store the old hub caps. He says yeah, got a box right here. Free.

So I proceed to buy 4 toyota rims, install almost new tires I got for 40$.

Come to her house, take out a big ass jack cuz we had just had our first snow fall. She said what are you doing with that? I said what?

Are you not supposed to jack one wheel at a time? She said. I said, your father got through to you. But in this case, this 2 ton jack will lift one of this echo. It will balance.

She backed up. Still has not drove the damn thing. When I put the hupcaps on it. I ask her if she like the wheels. She said they look like plastic. Ever seen a guy do a face palm? This is what it looks like,
 

infj23

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#22
Great face palm! This has been the most entertaining thread!

So here is the latest: the CEL went out today. Dashboard is pretty once again. I don't know why, but the thing "fixed" itself. Happened to have my scan tool with me and the Bank 2 Number 2 O2 sensor is putting out good numbers. It used to be steady 0.00 but now fluctuating between 0 and .8ish.

This suggests to me that the O2 sensor and cat are good and that Nickb2's idea of a bad wire somewhere is the deal. When I have the energy and time, I'll go a-hunting.

Any common/particular places I should look first?

Thanks!
David
 

infj23

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#23
Finally able to get into the car some more and see what I could do with the schematics graciously provided by nickb2.
My multi-meter probes were not small enough to contact the leads in the ECM, so I could not check anything there. Those were tiny holes!
Both the ground wire sides of the O2 connector showed an ohm reading when taken to a vehicle ground. The other two wires showed open (no reading) when taken to ground.
I may try again some day, but ran out of time today.
Thanks!
 

infj23

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#25
Here's the latest!
Got the piercing probes that grcauto recommended. Great fun!

After my failed effort (my most recent post) to check the wiring, the next time I started the car, it ran great. The CEL stayed off. When the O2 sensor problem is present, I can sense a very slight rough idle. That was gone--idle was smooth. That lasted 3 days. Then, I drove through the car wash. At the next red light (only .1 mile from the car wash), I felt the rough idle. Sure enough, the CEL came back on soon thereafter. Same code (P0157).

So now, time to check the wiring with my fancy new piercing probes.
Probing the connector that the B2S2 O2 sensor plugs into:
*connector 1 (HT) to ground: open (no connection)
*connector 2 (+B) to ground: closed, 0 ohms
*connector 3 (OX) to ground: 1500 ohms
*connector 4 (E1) to ground: closed, 0 ohms

*connector 3 (OX) to OX2B (pin 29 on E9 ECM connector-black wire): open (no connection). Per schematic, if I am reading it right, this should have shown ohms--a closed connection with some resistance
*connector 1 (HT) to HT2B (pin 33 on E9 ECM connector-yellow wire): open (no connection). Per schematic, this should have also shown ohms--a closed connection with some resistance
*negative battery post to HT2B (pin 33 on E9 ECM connector-yellow wire): .164 ohms
*negative battery post to OX2B (pin 29 on E9 ECM connector-black wire): open (no connection).

After doing all of these with the multi-meter, cleared the codes and started the car. While the car was running, I had the scan tool connected. The O2 sensor (B2S2) continued to show 0 (zero) volts. My assistant:
*shook the joined connector--no change.
*sprayed carb cleaner on the connector--no change.
*unplugged the connector. Interesting! O2 sensor B1S2 immediately dropped to ZERO volts. Should that have happened? Should unplugging B2S2 cause B1S2 to drop to ZERO volts?
*reconnected O2 sensor B2S2. B2S2 stayed at zero volts and B1S2 began operating normally.

CEL still on! B2S2 still showing zero volts at all times. What do I try next?

Thanks so much for any help!
David
 
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billr

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#27
Sounds like you are getting stuck here, so I'll toss out some general stuff, but keep in mind it isn't specifically pertinent to you system.

As "grcauto" said, reading of ~3V on the upstream sensors hints that those are WB sensors. Range for WB sensors is often .5-4.5V or 0-5V, or 1-4V; with low voltage meaning rich and high meaning lean.

WB sensors can be crudely checked by removing them from the exhaust, still electrically connected, and running the engine. With the sensor out in open air you should get a voltage approaching 5V because the free-air it is sensing has plenty of oxygen and is quite "lean". Then, flood the openings of the sensor tip with any non-oxygen gas. Argon or nitrogen will work fine, but so will propane from an unlit torch. With the sensor seeing little-to-no oxygen, the scanner reading should approach 0V because it is quite "rich". I'm hoping you may even be able to see the voltage reading "scan" from 0 to 5 as you wave the non-O2 gas across the sensor

Yes, I would expect disconnecting a sensor would show as a "0V" reading on the scanner. It would be great if somebody has a chart showing what the calibration is on your specific WB sensor; so we could tell what AFR that 3.3V means.

Watch the short-term fuel trims as you drive the O2 sensor nuts like this; I would expect some pretty wild trims trying to correct these fake readings!
 
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infj23

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#28
I am pretty sure the O2 sensor is good. I have replaced the sensor (more than once) and the problem recurs. It seems to me the problem is a wiring problem, not an O2 sensor being good or bad.
My observation about the O2 sensor going to zero volts was that Bank 1 Sensor 2 went to zero when a different sensor, Bank 2 Sensor 2 (which was already at zero volts) was unplugged. B1S2 was working fine but it went to zero when B2S2 was unplugged.

And yes, the fuel trims are going nuts trying to correct the bad reading. I am losing about 4mpg, get occasional hesitations, and a rough idle. As a result, sometimes a misfire code sets.

I'm absolutely no expert in this stuff, but it seems I should have had continuity in the lines between
*connector 3 (OX) to OX2B (pin 29 on E9 ECM connector-black wire)
and
*connector 1 (HT) to HT2B (pin 33 on E9 ECM connector-yellow wire).

Does something happen to those wires between the O2 connector and the ECM? Or is that a straight shot--two plain wires between the O2 connector and ECM--with no branches off, or relays or resistors or switches in the line? If these two connections (OX and HT) go directly to the ECM (OX2B and HT2B, respectively), can I just run bypass wires from the two O2 connectors to the two connection points (pins 29 and 33) on the ECM to ensure the signal is getting from the O2 sensor to the ECM? Would that work?

And one more question: if I am not able to figure this out on my own, I'll need to take it somewhere. Would a good, reputable, high tech garage be able to handle this, or would I need to get to the dealership?

Thanks to all!
David
 

billr

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#29
What I was describing, although "crude" regarding objective numbers, would be checking the entire WB O2 system; everything from the sensor through all wiring/connectors, the PCM, and back out the OBD2 port to the scanner. That may give far more clues than just swapping in a new sensor.
 

kev2

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#30
SOME INFO - sorry I did not follow this thread, :( I have some lexas info attached hope it helps I just saw a wiring overview
that might help - otherwise light reading for you.

I do feel bad asking as it likely has been addressed the AF sensor was from Lexas aftermarket is problematic.
Later I will look time permitting for TSB's...
 

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