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02 Highlander: Weird A/F (02) Sensor Glitch

3K views 18 replies 3 participants last post by  Wolfrequiem 
#1 · (Edited)
Well, I would probably still be lurking, but have run into a snag that I can't seem to find a resolution for (please help!).

The CEL on my mother's 02 Highlander (FWD V6) lit up years ago. Bad upstream sensor. She never changed it. I went to a local store and had them check it and came back with a P1135 *and* P1155 code, I think it was, and am going by memory from what the guy told me, as he just said they were both bad (though I did see B1S1 and B2S1 on the scanner, I do remember that though I can't remember the codes). Anyway, I replaced both with OEM Denso's, and unplugged the battery when I did (part 89467-48011 on each). Now, with two new sensors in, the CEL did not reset, and I cannot get it turned off. I went back to the OBDII scanner, and still came up with a P1135 and P1155. The woman at the local auto parts store said this time that I had to use an actual scanner to reset it, that draining the battery would not work. Two questions then:

1. Is she correct, as that doesn't seem right? And I don't seem to see online where that is the case, with it looking like the ECM drain should do the trick.

2. If she is correct, would one of the cheap Bluetooth model scanners work okay, perhaps the ELM327 (I drive older model vehicles and don't need one, nor need to invest in an expensive model--my dad died and my mom bought a newer car b/c this one is getting older and she's afraid of it getting older without him around, so she is selling this one is why I'm trying to fix it; so I need it just the once).

3. THE WEIRD THING is, just in case this matters: The clock and on/off lights on the dash recirc button, a/c button, and rear defroster button seem to be tied into this thing somehow, in case that points to a bad relay or bad a/f fuse under the hood. The clock has been out for years, as long as the bad 02 sensor she rode around on, and in going to see if I could get to the sensors, I unhooked the old bank 2 sensor 1 without disconnecting the battery, just seeing if I could (I didn't mean to pull it all the way out). When I plugged it in again, the clock worked, the on/off indicator lights worked on all three of the above again, etc. But just for a day or so. And the backlit lights work on them all the time anyway. I have seen this issue brought up online, but never with resolution or an explanation.

So, does that add anything to the mix? I'm thinking the drained ECM, leaving the battery unhooked for 20 minutes or so and flipping the ignition on/off a couple of times should have reset the thing. But maybe I'm wrong. If it is more than the 02 sensor, then does this above about the clock seem to point to anything specific, like the a/f fuse (the big one that can't be checked by sight like the little ones), or the a/f relay??? Bad ground maybe? Heck, man, I'll owe you guys big if you can tell me what to do, as I seem to be coming up blank on this particular issue, i.e., with the clock being affected by it.

Thanks a million to anyone that chimes in.
 
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#2 ·
Well, I would probably still be lurking, but have run into a snag that I can't seem to find a resolution for (please help!).

The CEL on my mother's 02 Highlander (FWD V6) lit up years ago. Bad upstream sensor. She never changed it. I went to a local store and had them check it and came back with a P1135 *and* P1155 code, I think it was, and am going by memory from what the guy told me, as he just said they were both bad (though I did see B1S1 and B2S1 on the scanner, I do remember that though I can't remember the codes). Anyway, I replaced both with OEM Denso's, and unplugged the battery when I did (part 89467-48011 on each). Now, with two new sensors in, the CEL did not reset, and I cannot get it turned off. I went back to the OBDII scanner, and still came up with a P1135 and P1155. The woman at the local auto parts store said this time that I had to use an actual scanner to reset it, that draining the battery would not work. Two questions then:

1. Is she correct, as that doesn't seem right? And I don't seem to see online where that is the case, with it looking like the ECM drain should do the trick.

Some times disconnecting the battery or resetting the ECU works. But in my experience you need to drive it for a bit so the sensors can do their job. Recently replaced my cat on my '01 I4 HL and cleared the codes right away which it came back and then disappeared after a week of driving.

2. If she is correct, would one of the cheap Bluetooth model scanners work okay, perhaps the ELM327 (I drive older model vehicles and don't need one, nor need to invest in an expensive model--my dad died and my mom bought a newer car b/c this one is getting older and she's afraid of it getting older without him around, so she is selling this one is why I'm trying to fix it; so I need it just the once).

Better is toyota techstream. Those generic readers are too broad in their reading. Techstream literally tells you exactly what's going on. There are generic OBD2 to USB cables you can find online that come with techstream.

3. THE WEIRD THING is, just in case this matters: The clock and on/off lights on the dash recirc button, a/c button, and rear defroster button seem to be tied into this thing somehow, in case that points to a bad relay or bad a/f fuse under the hood. The clock has been out for years, as long as the bad 02 sensor she rode around on, and in going to see if I could get to the sensors, I unhooked the old bank 2 sensor 1 without disconnecting the battery, just seeing if I could (I didn't mean to pull it all the way out). When I plugged it in again, the clock worked, the on/off indicator lights worked on all three of the above again, etc. But just for a day or so. And the backlit lights work on them all the time anyway. I have seen this issue brought up online, but never with resolution or an explanation.

This is odd. I've hacked up my heating controls over the years due to bad soldering joints, bulbs burning out, and connection issue but nothing close to what you described. I'd try to see if you can get one from a junkyard and seeing if its the controls itself.

So, does that add anything to the mix? I'm thinking the drained ECM, leaving the battery unhooked for 20 minutes or so and flipping the ignition on/off a couple of times should have reset the thing. But maybe I'm wrong. If it is more than the 02 sensor, then does this above about the clock seem to point to anything specific, like the a/f fuse (the big one that can't be checked by sight like the little ones), or the a/f relay??? Bad ground maybe? Heck, man, I'll owe you guys big if you can tell me what to do, as I seem to be coming up blank on this particular issue, i.e., with the clock being affected by it.

Get techstream first is my advice. That's been the best investment for my fleet of Toyota's and family's Toyos and Lexus'.

Thanks a million to anyone that chimes in.
 
#3 · (Edited by Moderator)
Camry, thanks a million. And, YES, it is odd, but it can't be coincidental, which is why I was thinking a relay or fuse. I have heard a few others say drive it, so I can do that and come back, if need be, as, yes, it resets for about two seconds, then comes back on.

And IF I am finding the ones you're talking about, that is within my price range and I'll go with your suggestion. I'm not sure if I am in violation posting the link below, so please forgive me Admin if so. I have seen people link to things, as long as its not advertising I'm thinking. Anyway, Camry, I'm not sure which one to necessarily go with, but here are a couple that seem to be what you mean (I think). Let me know. And, thanks, again.
**Link Removed**

I mean, is there a certain kind or brand that's best? I don't have a laptop, but I can borrow one from family, I think.
 
#5 · (Edited by Moderator)
Hmmm, the heater controls I do not think run off a relay, maybe the fan motor but that's about it.

The **Removed** link you posted definitely shows what I have. Doesn't matter which one you buy, they're all generic with a cracked version of techstream (I do not endorse this). But you really need an old computer or laptop with windows XP or any windows 32bit operating system. It takes a bit of work to get it working on the newer windows like 7 and 10. This sounds like more work then it needs to be but trust me, this is miles away from any code reader you can get plus it works to program keys and can be used on Lexus. Techstream was specific enough to help me diagnose my failing cat instead of forking up money for 4 senors (mix of A/F and O2) which my sensors were fine although I changed them anyways.

Also, yes, you can clear codes with this cable. Also personalize your car like turning off the seat belt warning chime, see live stats of your engine, and change different features that are available to your car.
 
#6 ·
Man, I'm glad you came back and said that. Oddly enough, I do have a box (desktop) that has XP still on it. It would take me a little doing to get it ready, but I could probably make that work, putting it in the shop near the thing. Wow, I am so glad you came back and told that. Thanks a million.
 
#8 ·
A $15 bluetooth scan tool and the Torque app on your phone or a Windows PC equiv., will allow you to clear those codes, *if* they are indeed past codes and not indicating that A/F sensor heater circuit still has problems( P1135, P1155).

While I suppose it is possible for the heaters of both bank 1 and 2 A/F (upstream)sensors to fail at about the same time, I'd think it is rare. Replacing both sensors would not be my first reaction.

If measuring the sensors to verify they are getting heater power is beyond your comfort level, checking out (or just replacing) the A/F HTR relay and the 25A A/F fuse would be the first things I'd look at.

Don't think the A/F sensor circuit is shared with any other vehicle accessories.
 
#9 · (Edited)
Thanks, AV. And my post was already so long, I didn't go into the details as much to save space: The first sensor--I think it was Bank 1--went out ages and ages ago. For some odd reason, my dad, who was a Nazi on keeping a car up, or my mom's anyway (he was in the tire business for years and years), didn't bother. I think because they cost so darn much and he wasn't going to pay it on principle. Whatever the reason, I actually got the car from her and had the codes checked here a few months ago, to verify what I needed--and it was Bank 1 Sensor 1 then, though I don't think the guy told me the code that time. Well, I didn't get to it right away and, for some sneaking reason, thought I ought to have it checked one more time (oh, I know, because I couldn't remember what Sensor--lol). Well, just here in the last few months, the second one failed, and I caught it when I went back. So, they didn't go together. In fact, quite the opposite. But, she bought a newer model Avalon and I'm going to sell this one for her to offset the cost and know people don't like check engine lights. So... and someone is going to get a good deal on it: I have all the paperwork and EVERYTHING has been done on it in the last few years or so. The tires are still new and come with free rotation and balance, it has a viper car alarm and remote control starter (on the key fob), you name it. Leather, power everything, and every seal, gasket, the timing belt, water pump, brakes, a/c compressor, two way sunroof with no leaks, full spare that's new, and an almost new second spare to go with it (though that one isn't mounted)... it's just got some dings in it, etc. 228K, and if someone takes care of it like my dad did, no reason not to get 500K out of it. :) But... it's a Toyota, too. So, anyway, being a noob on them, it made more sense that they were both bad in that context--one went out probably at 150K maybe (I don't really know), and now this second one at around 220K.

Mom shouldn't have bought the newer car (a 2013, I think), but--just to be honest--she kind of got to feeling sorry for herself, having just lost Dad, and went into that "I deserve it" phase, justifying fear of reliability on this one, which is totally unfounded. She just had to fork over a couple of high dollar bits that came time and it scared her. (And I'm not being mean to my mom in saying so, just being honest, as it's understandable.)

And I have sort of seen people checking them--a few videos, even--but would have to buy the meter and the whole nine yards. Which might be doable.
 
#10 ·
Attempt to clear the codes with a scan tool of some sort. Auto Zone may be able to clear the codes with their scan tool. If codes come back, check the A/F relay fuse.
 
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#12 ·
Back for a follow-up and any further suggestions anyone might have.

At this point, I have:

1. replaced the a/f sensors
2. driven it to see if the codes would clear (they did not)
3. used a scanner to clear the codes (they came back on almost immediately)
4. replaced the a/f relay under the hood in that fuse box with an OEM relay (the one for my horn and a/f are the same type, so I just swapped them out, instead of replacing them)
5. cleared the codes again (they came back on again almost immediately)

So, I have two new a/f sensors in the thing and cannot clear the codes. Next line of offense here, anyone???
 
#13 · (Edited)
And, I'm not sure I'm doing it correctly or not, but on the old sensors, using a multimeter to check ohms, at 2K ohms (I don't have a 200 setting on the one I have), the old sensors come back 1.0, while the new ones come in at .007 ohms. Does that mean anything? I'm thinking I may be using it incorrectly, as the setting for cool sensors is supposed to be 0.8-1.4 ohms if the sensors are good. Or does that mean the new sensors I bought are bad and are not getting enough resistance? If so, I need to get with the manufacturer. Thanks, in advance, for replies. On voltage, I'm getting 6.67 V from bank 2 sensor 1 to the battery, checking the harness (and I should add, I have only checked just bank 2, since bank 1 is so hard to get to).

The weird thing is, if the old sensors are showing good, then why did they trip the CEL? That makes no sense, especially as they did so independently of each other, at different times.
 
#14 ·
If codes P1135, P1155 come back after they are cleared, then the PCM is convinced the A/F heater circuits aren't drawing current. Other than the relay and fuse I mentioned in earlier posts, it'll mean some deeper diging into the cause. Could be a bad connection at the fuse block, poor ground connection at the PCM, bad PCM.

The PCM uses duty cycling of the ground side of the A/F heaters.

Here's a good simplified schematic:

http://www.autocodes.com/p1135_toyota.html


On a 2K DVM scale, unless you have a 7 digit DVM, then .007 ohms wasn't the reading. In any case, you certainly don't have two bad ORIGINAL sensor heaters and two bad NEW sensor heaters. The problem is in the circuit.

If you conenct the sensors back up and idle the car, back probe the heater wires (both wires are black on my A/F sensors), at either the A/F sensor or back a the connector.

Maybe easier to pierce the wire insulation on the car side of the connector block as the insulation is PCV vs telfon/silicone on the sensor wires. If your probes aren't sharp, then insert a sturdy straight pin into each wire. Make sure the straight pins are well away from each other and never touch

You should read about:

+13v (whatever the running battery terminal voltage is) between one heater back wire to car body ground (battery, chassis, engine block).

+2v to +8v between the other black heater wire and ground.

When I say "between", I mean BLACK DVM probe on ground and the RED probe on either heater wire.

If you fail to find the +13v on either heater wire, then start tracing the power path from the heater wire back and through the fuse box,

If BOTH heater wires measure +13v, then there is an open circuit back to the PCM. If the PCM is able to pulse the heater, that heater wire will ALWAYS read lower than the battery voltage.

At idle, since the exhaust gas flow is insufficient to raise theA/F sensor temp much, the A/F heater is driven harder to keep the sensor at about 1200F.

On a cold start, the PCM prompts for maximum heater current to get the A/F up to temp quickly. The PCM wire to the A/F heater will probably measure 1 to 2 volts (between heater wire and ground).
 
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#15 ·
Correction

Update, AV, though before I had a chance to read your post (thanks a million for chiming in again):

1. I bought a new multimeter. I needed one, anyway.
2. From the "hot wire" to the battery, with the ignition on but the car not running, I get 12.67V. That's putting the red probe in the female "hot wire" socket on the bracket and the black probe on the negative battery terminal (in case I'm doing anything wrong). I got 2.5V on the other female terminal that matches the second heater pin on the sensor. I didn't realize that was useful, but don't have 13V on both, then, through the bracket, but I didn't have the sensor hooked up and the car was not running when I did that.

That was using the 20V setting on the multimeter, in case that matters.
3. This doesn't seem needful now, but I got 6.5 Ohms for the hot sensor on one terminal, and switching them up got 2.52, I think it was. The first measurement is red probe to what would be the hot wire into the heater and the black on the other terminal. I'll plug it back up and try to do what you say now. Sorry about that.

And I could be wrong on the codes they were giving me originally, but I DID keep the old sensors that I could stick back in, at least, on the front, and see what the code it gives me is. The stupid OBD scanner I bought crapped out on me first thing, though, so I'll have to buy another one (I bought the Walmart cheapo, thinking it'd do for a one time need... and it didn't let me scan twice before the stupid thing died). lol
 
#16 · (Edited)
Done and done on bank 2 sensor 1, which I'm thinking may be enough:

1. Skinned just a tiny, tiny place on each lead to the heater on the ECM side of the female harness.
2. Attached red probe to each wire in turn, black COM probe to the negative battery terminal.
3. Car idling.
4. Red probe to black wire: 14.08V. Red probe to red wire: 14.33V.

So, what would I replace with that going on and both the fuse (25A) and relay okay? Wow, this is about to hurt my feelings on the money, isn't it? I'll try to go back and do the same for bank 1 sensor 1, I just wanted to add this info for it to be out there in the meantime. Thanks, again.

UPDATE: Bank 1 Sensor 1

Same procedure. Same result: I'm getting 14.33V on the red and 14.32V on the black on bank 1.

RESISTANCE (is futile?):

In case it matters: Granted the manifold is hot, but bank 1 gave me 7.4 ohms on the 200 ohm setting on the meter, and bank 2 gave me 6.5 ohms on the meter. I'm thinking that indicates they are fried?


And would it be helpful to unplug both sensors and run the car without it until I resolve the issue, e.g., to make sure I don't burn them out running them open like that? Thanks.
 
#18 ·
Solid measurement report! The heater is not drawing any current. Seriously doubt it blew up either the original or replacement sensors.

You have battery voltage at the sensor, which means the battery side connection is good.

Looks like an open circuit from PCM to A/F heaters, or the PCM is defective.

I'd start working my way backwards from the sensor (pick either A/F) to the PCM to see if any of the connctions are defective. Like disconnect the connectors, carefully examine pins/sockets, tug on wiring, look for fraying, rat chewing. It'll be tedious work.

If you are brave, you can cut to the chase on troubleshooting wiring: Locate the PCM behind the glove box. Unmount it to where you can probe the back of the harness connectors. With the car running, if pins 3 and 4 have a steady 14v at the back of the PCM (black DVM lead on a body ground), then either the PCM is defective or one of the ground connections to the PCM is defective. I'm not sure which of PCM ground connections the heater flows through.

If pins 3 and 4 have a few volts or unsteady voltage, then it points to an open circuit between PCM and heaters.

Find an electrically handy DIY friend, for moral support.
 
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#19 ·
Thanks, AV. I'll report back on what I find. I do have one question for clarification: Each sensor has four wires, two black, one blue, and one white. The two black wires are the heater, right? That's the assumption I've been going under, from a post where I saw it listed as such here (just want to make sure, so that I'm not reporting falsely or chasing my tail, I guess). Here's the link at ToyotaNation I originally got my info from:

http://www.toyotanation.com/forum/2...8427-2002-sienna-p1135-p1155-help-please.html

In the meantime, seriously, thanks a million for sticking with me on this one. I'll let you know what I come up with, and will probably do as you suggest by cutting to the chase, as there is so little room in the engine compartment on these things for checking the wiring. The odd thing is, just to ask, if that's the case--the bad circuitry on it--then that means the *whole* PCM has to be replaced, right? Or, in other words, you can't replace just parts of it, I guess, is what I'm asking.
 
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