2ks

By the way, when you get the sensor situation fully straightened oput, IF you still have the lights, let me know and I'll give you that link to deal with it.[/QUOTE]

Thanks for all your support, Sorry if it caused you a headache, i just couldn't get past the DTC code list having it as the rear sensor. Funny when i was talking to the dealership this never raised an eyebrow when i told him what codes i had, this was the diagnostic tech i was talking too as well. You seem to know alot about these cars/trucks/SUV's, did you ever work for Lexus/Toyota? Again thanks. I will tell everyone i know about using Denso's only on Lexus/Toyota. I was also told by a co-worker that he has to use Lexus spark plugs or he has problems, they are more costly but they work. Guess I will be putting my other sensors on E-bay to try to re-coop some of the $60 spent on cheap sensors.

code58

No, Kevin, worked for quite a few different brand of dealerships, but never T/L. Just that I spent my life in automotive work.
It's a shame that P1155 code is still listed incorrectly after all this time because I'm sure it's caused a lot of people grief. I used that sites function to report mistakes so that they could be corrected, probably 2 or more years ago and nothing was ever changed.
Having worked in dealerships most of my life, I am sorry to say that there is a lot of incompetence there too. Even not real bright people do get hired and do have to eat... unfortunately.
I am just the mechanic (unpaid) for my DIL's RX. My wife drives a Camry and I drive a Ford P.U. Being a detail orientated person, when there was 1st need for major maintenance work on the RX, I had to do a whole lot of learning, in a hurry! I DON'T like chasing my tail, so I try and make sure I know what I'm doing the 1st time around.
Concerning the Denso parts, It's just that they are some of the finest parts I've ever seen produced in my life. That goes for the other names that T/L uses to build their vehicles. Aisin, Koyo, Mitsuboshi, etc. I believe both of the Camry's my wife has had came with NGK Iridium plugs, which are actually equal to Denso. That's the reason that OEM is the ONLY thing I'll use on T/L. It's the reason a 4 cyl. Toyota P.U. or Camry will go 300-350-400K mi. without even a whimper, if maintained properly.
By the way, there are plenty of places to buy OEM T/L parts at much less than retail.
Remember what I said about the lights. I'm not giving it to you now so that you don't use it unless you NEED to! You know the old saying: "If it ain't broke fix it till it is"..... no, wait, I guess that's "If it ain't broke, DON'T fix it!".

artbuc

[QUOTE=2ks;7078673 I was also told by a co-worker that he has to use Lexus spark plugs or he has problems, they are more costly but they work. [/QUOTE]

Totoya/Lexus does not make sparkplugs, of course. Your friend probably means to use plugs recommended by T/L which will be NGK or Denso. Based on a technical report I read on the developement of the Denso Iridium plug, I would never use anything but Denso. They are designed to last 200k miles BEFORE performance drops off. Quite incredible when you think about it.

code58

Art, they are an amazing plug, aren't they? I will say, both the RX and the '02 Camry and '11 Camry have had NGK plugs (OEM from factory). I still have the plugs I removed from the RX at 97K mi. and had I looked at them before I got the new ones, I never would have changed them. They look almost new and still guage exactly factory specs. I know you're not supposed to gap iridium plugs, and these had definitely never been out. With truly high miles driving (60-75K per year) I believe they would last the life of the vehicle. Hardest metal known to man.

hypervish

My plugs looked like new when I replaced them last year when they had about 160k miles. Didn't check the gap to see if it was in spec.

2ks

I just ordered the Denso A/F (o2) sensor 234-9009 for the front B2S1 location. All this time i was saying in this thread that the cheap sensor in the front position is "happy" and not throwing a code was a MISTAKE on my part. Just couldn't get past (didn't understand) that the obdII code list i was using was wrong, and the net has multiple code lists that are WRONG, matter of fact the only place i have seen that P1155 is the front sensor is here in this forum. I will jumping for joy if the new sensor comes in and the code clears and all the effing lites go off on my dash!!!!! If the code does not clear then i will be back here with some great confusion and very angry at Lexus/Toyota for putting me thru this in the first place.

I have always liked owning toyota, but this is the first Lexus for me (wife's car). It is usually the road trip vehicle and rides incredibly smooth for a SUV. I have a few other minor problems with it that need to be addressed in another thread some day to include the temp mixing servo's clicking/ squeaking noise when turning the steering wheel, and a slight wavering vibration at about 62-65mph. But all can be addressed in time. Thanks for all the help to Code 58 and Art.

hypervish

The squeaking noise when you turn, is due to the lack of lubrication where the steering column goes through the firewall (by the pedals). Just spray some silicon lubricant there, and the noise should go away.

code58

.

Remember Kevin, I said IF the lights don't clear with the new sensor, come back with the exact situation (what lights and what codes) and I'll give you the link that may well deal with that. Keep calm, a level head works a lot better than a hot head. Best of luck!

2ks

Put the new denso sensor in the fwd position and all is good!!!! No lites on the dash at this time and they seem to be gone. Stupid OBDII code lists. I know now for the next time and any one i know with a Lexus.

artbuc

Congrats on your successful repair! Now, please don't take this the wrong way, but a modest internet search would have steered you to the correct codes. Good learning for me too as your problem motivated me to do some of my own research.

code58

Art,
I have seen DTC's that had the correct listing for P1155 (B2S1) but not very many. MOST of them have the incorrect (B1S1) which is the reason I figured it likely came right from a mistake on T/L listing. Sad part is I used the onsite form for reporting the mistake and it was never changed. I could only assume the site was not monitored. Can you inagine how many people who aren't really knowledgeable about automotive have taken the mistake like Kevin did and the nightmare it causes. I realized the 1st time I looked at the list that it HAD to be a mistake. Especially now that the original years (1st few) are often needing their 1st. A/F sensors the mistake is going to cause more headaches like Kevin's. Common sense (you say that's in short supply?) is your friend.

code58

Kevin,
So very glad hte problem is resolved. I am ALWAYS happy to see success. May it be many months (or better yet years) before you see another CEL! Keep in mind what I said about not taking the DTC's to the bank. (sometimes they're counterfeit ) They are at best, sometimes, only a roadsign, not a laser. Also remember what you learned about cheap A/f ratio sensors- you get what you paid for.
Also remember what I said about the light combination, if you can't get 'em to stay off. My brother had to use it on his '05 Highlander.

artbuc

Yes, the last time I checked, Lexus had not corrected the electrical troubleshooting procedure for the IACV in the official 1999 RX300 Repair Manual. I bought a brand new factory IACV for around $250 before I realized the manual was wrong. To their credit, Lexus reimbursed me for the new IACV. I assume Lexus looks at it this way: the number of DIY folks who a) have a Repair Manual and b) would attempt to electrically troubleshoot their own IACV must be very low. Why incur the cost of correcting the Repair Manual for such a small group? Now, the A/F sensor DTC error is not as understandable because it is a much more common problem. The Repair Manual is very useful but you must have some basic understanding to use it effectively. I used to watch a few DIY shows on TV (before they became uninformative entertainment shows). Even then, I often told my wife, if you don't already know what they are telling you, you should never attempt the project.

rxtaylor

When it was all said and done, just needed to replace the O2 sensors in both banks.

Strange though, the code reader only gave me 1135 (I'm sure 1155 wasn't hiding in there anywhere) until after I changed out Bank 1 Sensor 1. Then as soon as that new sensor was in, the 1155 code popped up immediately. Just putting in a new sensor there in Bank 2 Sensor 1 took care of that problem as well. Been driving on the two new sensors now for almost 2 weeks. No new codes. Engine does sound like its running at a slightly higher rpm though but might be my imagination.

Part of me says it makes sense that upstream O2 sensors in a V-6 would likely go bad in pairs... part of me wonders if the computer compares the signals of the two upstream sensors to one another as well as to the downstream sensor, and it's possible the new one made the old one just look bad in comparison. Either way, at 170k on the engine, it doesn't surprise me that I'd have to replace both of them anyway.

I've only ever owned domestic 4 cylinder and inline-sixes so working on a Toyota (and a V design) is new to me. I'm taking away four lessons away form this whole mess.
1. Always double and cross-check the OBDII listings and make sure they are correct (this 1135/1155 snafu is the only one I'm aware of, but I'm sure there are more).
2. If you've got to replace the upstream O2 sensor in one bank, don't be too surprised or frustrated if you wind up having to also do the other bank.
3. If you are replacing both upstreamO2 sensors make sure they are the same brand, and by all means choose DENSOs if you've got a choice.
4. Toyota engineers are pretty good. If you're not getting there results you are looking for from your "repair"... it's not the car's fault. You're the one whose made the mistake.

Thanks to all for your constructive advice.

code58

RX,
That is a thoughtful and well reasoned post. I normally wouldn't recommend changing both sensors at the same time with a lower mileage vehicle, but I do agree with your reasoning at 170K mi., it was time for both, even IF both weren't coding. Very happy to hear of the success and thanks for the helpful post.