OK guys, I could really use some advice from the experienced techs on this forum! Back in the spring somehow I let the coolant run low and for the 1st time I watched the temp gauge climb to the HOT area of the dial. I quickly pulled over n shut it down. Got the car fixed (R/R radiator) but the "chk eng" light came on with a P0135 code, O2 sensor b1 s1. Well, I wound up in the hospital, there went the summer, and emissions testing was Aug 15. Knowing no better, I cleared the code with a reader n went to testing-they said there wan't enough data in diagnostics to perform the test, they gave me 30 days extension. Anyway, I was almost convinced that b1 s1 was the o2 in front manifold by radiator, but reading many other posts is it really the one between the firewall and the engine on that manifold? Following back surgery, I could probably do the easy one in front, but *ouch* dunno if I could handle the 1 at the firewall! Anyone one know for sure which one is b1 s1? Thanks for any help/advice! Gary. (96 avalon xls) PS - no drivability issues, *maybe* I noticed slightly better performance, no noticable mpg change...
Yeah Gary, bank 1 is the rear bank. For future reference, one can figure out which bank is which by following the intake runners. Bank 1 always contains cylinder #1, so whichever side of the engine the first intake runner goes into will be bank # 1.
I can't recall the engine bay layout at the moment, but I seem to remember replacing the rear bank sensor on some of those older models from the top. Take a look straight down just to the right of the master cylinder and see if you can't find the sensor and possibly put the open end of a 7/8 wrench on it. If not, the car will need to be in the air. Post if you need a hand.
Qslim- Thanks very much for the reply! Maybe if I can spray some liq wrench on it and use an extension I may give it a try. If the ol' back starts "poppin'" I might be able to get a neighbor to give it a try. Thanks again!! Gary.
Qslim- Thanks very much for the reply! Maybe if I can spray some liq wrench on it and use an extension I may give it a try. If the ol' back starts "poppin'" I might be able to get a neighbor to give it a try. Thanks again!! Gary.
No probelm. One thing I forgot to mention is the propensity of those rear sensors to seize in their threads during removal (only happened to me a few hundred times). It's a huge pain in the ass and a road you don't want to go down, so lube that sucker down with some sort of penetrating fluid and let it marinate for a few hours at least, and avoid removing the sensor when the pipe is hot. This'll increase your chances of getting that thing out with the pipe threads intact.
Oh my God! That's an awfully tight spot for that to happen! I can't imagine getting thru that if it seizes back in there! Now I'm wondering if I should tackle it or not. I know the dealer would do it right, but just worried about the $$$$. There is a mechanic I use when I don't have the tools or equipment to do the job, maybe I'll go that route. I've been spraying it with liquid wrench once a day, hoping it soaks in, maybe I'll try and start it n see how it feels. Emissions testing gave me until 9/16/2007, and they said it'll take 2-3 weeks for enough data to accumulate after the code is cleared to do the testing, so I gotta do something pretty quick. I really do appreciate all your feedback, it's been really helpful!
Yeah, that rear sensor has given many a scraped forearm. If I recall correctly, you need to drop the subframe down a little to get to it if it seizes, so you'd be looking at several hours of labor instead of the normal hour or so you could expect from a technician. If you do take it to him you'll be doing him a favor by soaking it down first. Let him know, maybe he'll cut you a break!
OK, got a neighbor to replace the O2 and erase the code. Drove it that nite & the next day CEL came on again, this time P 0125, "Clsd loop fuel control Insufficient coolant temp". Looked under the hood for poss loose /disconnected hoses/plugs, found 1 plug off the master cylinder(?) Don't think this would be related, but I reconnected & cleared the code anyway & will continue driving. He replaced the O2 with a BWD os968, either from Auto Zone or Advanced for $140.00. It luckily (& with 3/4 can penetrating oil over 1 week or 2) came out real easy, new 1 went in same way, plug in, not universal. Could there be another prob? New o2 bad? Temp gauge goes to mid gauge like always, coolant OK, no drivability issues. Oh God, tomorrow is deadline for emissions testing! Thanks in advancce for any help/advice!
Well damn. Alright, 125 still relates directly to the o2 sensor, but in a different way:
po135 (your previous code) relates only to the heating element in the sensor that is responsible for getting it quickly up to operating temp. This new one of yours has to do with the output voltage produced by the sensor that is fed to the computer for fuel trim adjustments. The voltage from the sensor is supposed to cycle between .2v and .8v (roughly) about once a second. The computer is telling you that it is not seeing the correct wave pattern; the sensor's output voltage isn't cycling as high as it should. Here's a shot out of your manual:
I've never seen this code relate to anything other than a bad sensor. Unfortunately I don't have any experience with aftermarket stuff, and I don't recognize the brand you put in so I don't know what to tell you. Clear it and drive it. The detection conditions are in the pic above, so once you meet the requirements on the left (a, b, c, and, d), the monitor will have run and if failed turn on the CEL. CTP stands for closed throttle position btw. It just means that you haven't taken your foot all the way off the gas pedal. If it comes back on, see if you can get your cash back for a factory sensor or at least a Denso (who makes the factory sensors).
Qslim- I can't thank you enough for all the very valuable info you'vve taken the trouble to offer me. All your work is greatly appreciated!! I'll talk to the guy who replaced the sensor & see if the parts place offers Denso, if not we'll see what Toy wants (I think I looked once & it was around 250 or so). If I can get a good enough extension from Emissions Testing, maybe the WWW might have deals on OEM Toy parts. Thanks again and I'll keep ya posted! Gary.
check if your vehicle is ca. emission certified. if it is, the shop that replaced your o2sensor f'd up. The correct fix for a 135 is a replacement OEM A/F sensor. it looks like an o2sensor but functions completely differently. You don't monitor voltage on A/F sensors, if you hook up a scanner it'll just show you a fixed voltage. A detection circuit in the ECM detects the change and strength of current flow and puts out a voltage signal relatively proportional to exhaust oxygen content. Replacing an A/F sensor w/ an o2sensor will definitely cause a dtc125. But check other things as well that may cause it. bad tstat and/or bad ect.
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