O2 sensor (84-87)

[Brett5cent]

Hey i just bought my van a couple weeks ago. its running rich and when i located my o2 sensor on my exhaust, the other end thats supposed to plug in somewhere is just dangling. i cant find anywhere where it would plug in! can someone point me in the right direction please?

[blakebecker37130]

Hello,

Is the wire hanging and not connected to the 02 sensor, or is the wire connected to the 02 sensor and not connected to the harness? When looking at the wiring diagram the sensor wire runs back to the harness which runs back to the ECU. The harness branch is close to the air meter and mine had a brittle grey vinyl tube covering the 02 sensor wire. I just did this repair on my 86. When I bought the sensor, I thought the parts store sold me the wrong one. The one they supplied had male threads on the sensor. It turns out my van is registered as an 86 but actually has the 87 build as far as the exhaust, so it takes the single mesh shielded wire 02 sensor with the oval flange, gasket and two nuts. Also the previous owner or technician had broken the connector on the 02 harness branch, so a splice, solder, silicone waterproofing and electrical tape connection was made to complete the branch to 02 sensor circuit. An important thing to know which is not shown in the diagram is that the mesh shield wire needs to be grounded in order for the 02 sensor to complete the circuit. When I repaired mine, I discovered the mesh shield wire was corroded and not making a good ground, causing a check engine code 05 (opencircuit in 02 sensor). I had to strip the circuit back about 6-8 inches to find good mesh shield wire. I soldered a new circuit to this and grounded it on the intake manifold near the air meter, where some other circuits are factory grounded with terminals. This solved the issue and the light has stayed off and the van runs much better. I hope this info helps.

4805

Best regards,
Blake

[Rudy]

The other side of the connector is near the air filter box, toward the steering wheel on the engine side. It will be the only one that fits the 02 sensor, sporting a single conductor and a plastic tab to help glide it in.

[Brett5cent]

4807 4806

im just not seeing anything where it would plug in. it seems like itd be very obvious, but nothing, and near the airbox, im assuming you mean right in this area right?

[Brett5cent]

if anyone is able to show me a picture of where the o2 sensor plugs into the electrical, i would be totally stoked. sorry im new to this van, love the thing just trying to figure out everything! thank you so much! also i found this cut wire (coming out of split casing) that was hanging down toward where the o2 sensor is. maybe somebody cut off the old one, never spliced on new one? i dont know. wire looks to be about the same size as the one connected to the o2 sensor. 4809

[JPERL]

It looks like you are holding the correct wire in your last picture because there is no connector attached The 02 sensors from 84-87 that were single wire commonly broke off right at the plug.

[Rudy]

JPERL might be correct. I'll try to snap a photo of the connector for you and upload it when I get home.

[blakebecker37130]

The picture of the hanging wire looks like the mating conn for the 02 sensor? This circuit should just run up into the branch on the harness and go back to the ecu. The junction is right in that area by the airflow meter. Follow the hanging conn circuit and see if it is broken? It might belong to the branch you pictured with the YAZAKI stamp on it? If so make sure that when you repair it that you also pay attention to that shield wire I noted in my first reply. Please see the attached pic of what the factory spec connector looks like on my van.


4811

Best regards,

Blake

[Brett5cent]

ok i figured out whats going on. the male end of the connector, broke off at the wire, and was inside the female end of the connector that is on the opposite side of the wire of the sensor itself. i guess i look for a male end connector peice at the parts store and splice it on. thats what its seeming like...

[blakebecker37130]

I could not find one of those connectors at in my local parts stores. They may be available online? I'm sure you can find one at the salvage yard on just about any old Toyota, 1980's vintage. I opted to do as the technician did before me and hardwire the circuit. No more connectors. I grounded the mesh shield wire to the intake manifold where a series of factory grounds were already established. I then ran a single wire down to the 02 sensor and hardwired it by splicing, soldering, silicone waterproofing the splice and finally wrapping the splice with electrical tape. I then utilized some zip ties to pull the slack out of the way of the exhaust system and to keep it from coming loose or catching on something. I trust this repair just as much as the factory connection, if not better. I work for a big name Japanese wire harness supplier and am not at all worried about hardwiring connections. If the 02 sensor fails, I'll cut if off like a rotten banana and start over again:dance2:

Best regards,
Blake

[Brett5cent]

so what i did is bought a new sensor put it in, and spliced it into the wire that i am 90 percent certain the male end connector broke off of. it seems to be running alot better and definitley more power. i am still getting a code 5 tho. does it have to be driven for awhile for the codes to reset? i am also getting code 11. im still trying to figure out what you're talking about when you say the mesh wire and it needing to be grounded. the sensor i have is a single wire and and its nothing more than a stardard looking wire.

[Brett5cent]

got it taken care of, figured out how to reset codes! no more code 5! now to take care of the code 11.... thanks everyone

[Cali Cruiser]

o2 sensor replacement is pretty easy. You can purchase a direct replacement with the plastic connector plug already attached ($15 plug and play version)...or go the cheaper $6 version that requires you to cut off the old the connector plug from the old o2 sensor you will remove (leave a couple of inches of wire sticking out of the connector plug) and crimp the new o2 sensor to the old connector. A new gasket should be used to avoid an exhaust leak in the near future.

Safety first...be sure the car is in park or in gear, engage the emergency brake, look up behind the driver side front wheel, and you should spot the o2 sensor. It is held by 2 nuts. There is also a heat shield held by the 2 nuts. Follow the wire coming out of the o2 sensor to the connector plug. It is mounted up higher, but should be easy to access, even without raising the van on jack stands.

[dogger562]

O.K so I got a code 5 that indicates Ox sensor, the manual tells me how to check with voltmeter but it's says I need SST 09842-14010 does anyone know where can I find one? Or an EFI Checker SST09991-00100 ? The other questions I have is. Can I just pin the nidles to connector if so I would need a little more clarity if someone can help wich of the 3 connctors is it? I had same problem identifying for the check engine test. The thing is that the manual shows on pictures of the 3 and they look pretty similar at least the two larger ones. Any help is appreciated Dogger562

[AD2101]

I think this is one of those situations where you just pony up the $25 and get a new denso o2 sensor. I've never even heard of that SST but can almost assure it'll cost more than the sensor itself (if you can find it) and it's one of those catch 22's where it makes more sense to buy the part without troubleshooting further. If the SST says the o2 sensor is no good then you still need to buy the sensor and if it says the o2 sensor is fine (doubtful), then you're still out the price of the SST, so either way the cheapest route is just to buy the sensor and forgo trying to hunt down the SST.

Replacing the o2 sensor is one of those "replace if it's throwing a code/don't know history of vehicle" parts, at least to me. My guess is the new o2 sensor will clear up that code 5 but if it doesn't there are other options discussed on the site.

[dogger562]

Thank you for responding. I wanted to know if the sensor was good or not. Not so much to save money on it but to properly diagnose the issue because say, I have a good O2, then why I'm I getting code 5? or bad air/gas fumes? but I see what your telling me.. I honestly don't know anything about troubleshooting or maybe I'm just over thinking, that, say, O2 is good or if install a new one but because of other problem causing bad air/gas mixtures then it damages quick then I'm not solving the problem just quick fixing it. But your right it's going to be a PTA to even get close to finding any of them two specially the EFI Checker even dough it would be cool to have a checker, I think it can diagnose many things.

So $25 bucks?? The cheapest I have seen is $37 for Denso Ebay.

[AD2101]

Unfortunately, with older vehicles that have these basic types of computers and error codes, the best way that I know of (without a time machine or access to what Toyota techs had back when these were still new) is troubleshooting by process of elimination, AKA throwing parts at it until you fix it. At face value that sounds pretty crappy but there are always parts that are more likely to fail than others, and the FSM will always point you in the right direction. Here is the FSM information for a code 5 error on a 84-85 van:

6009

So, if it's not your o2 sensor, the next places to look would be the circuit and, finally, the ECU. Again, these o2 sensors are wear-and-replace-parts, and are subjected to extreme heat and generally terrible conditions. You only realistically get so many years out of these sensors before they give up the ghost and it's time for a new one. A chain breaks at its weakest link, and these typically are it when you get a code like this. Of course, if this turns out not to be the case, then the o2 sensor circuit and the ECU would be your next logical steps.

And I found the denso sensor on rockauto (http://www.rockauto.com/en/moreinfo.php?pk=991973&cc=1279694&jsn=366) for $22.79 + shipping. You can easily google a 5% off coupon for rockauto so I don't imagine it costing much more than $25 shipped to your door.

[dogger562]

Thank you, it does give me more clarity and defiantly makes sense, and thanks for the Rockauto tip. I'll be ordering one, and see what happens. Cheers! :thmbup:

[AnotherUser]

-- 1986 2wd --

The error code is showing 5 blinks.

#5 on the list - Oxygen sensor signal. open circuit in oxygen senor signal (only lean indication). 1. Oxygen sensor circuit. 2. oxygen senor. 3. ECU.

About a year ago my van was sputtering up hills and heavy acceleration. I put in a new O2 senor and it fixed this.

Currently there are no performance issues, just the check engine light coming on at times when I am going 50mph+

Could it be the newish 02 sensor again? Is there a way to clean it and what could be causing this?

Thank you

[boogieman]

what brand of O2 sensor did you use? brands other than denso have been known to be unreliable...

[AnotherUser]

what brand of O2 sensor did you use?

I had to return the first one I got because the flange didn't sit flat and stuck out, but I don't remember the brand I used. Is there a brand you should stay away from?

[llamavan]

-- 1986 2wd --

The error code is showing 5 blinks.

#5 on the list - Oxygen sensor signal. open circuit in oxygen senor signal (only lean indication). 1. Oxygen sensor circuit. 2. oxygen senor. 3. ECU.

About a year ago my van was sputtering up hills and heavy acceleration. I put in a new O2 senor and it fixed this.

Currently there are no performance issues, just the check engine light coming on at times when I am going 50mph+

Could it be the newish 02 sensor again? Is there a way to clean it and what could be causing this?

Thank you

Not only could it be the O2 sensor, but they often do throw a code exactly in that situation (50mph+). O2 seonsors are pretty affordable, so putting in a new one is a good first choice.

Gwen

[AnotherUser]

The wire coming off my van that goes to the connector that plugs into the O2 sensor has come off right at the connector

Here is a picture:

https://i.imgur.com/n9NwbOR.jpg

There is no wire on the connector to try and splice in a new wire. Would it be possible to try and salvage the old connector, or where could I buy a new one? Auto parts stores didn't seem to have this connector

[Cali Cruiser]

Save yourself the hassle and just cut off the other part of the connector and then use a butt connector to join the wires together. Add a piece of heat-shrink tubing onto the wire before connecting the wires together...this will help seal up the connection for extra protection from the elements. That is how the universal o2 sensors are installed. If you are concerned about future replacement of the sensor, you could use a spade style connector for easy disconnecting instead of a butt connector.

[AnotherUser]

Save yourself the hassle and just cut off

Yea, you're right. I wanted to keep everything stock and not have stuff wired in, but it would be a lot easier just hard wiring it. I ended up soldering it in.

[AnotherUser]

I have put a new O2 sensor in and I still get the same error code when going at highway speeds. There are no performance issues that I notice, just the check engine light going off and on at times.

Anything else I can try?

[timsrv]

I had that problem with my 86. I replaced the o2 sensor twice and yet that code always came back. Next I swapped in a spare ECU and the code still came back. Since o2 sensor is so close to the ECU, I installed a new wire to the sensor, then cut the old wire off close to the ECU and butt connected the new wire to the ECU harness. Job was easy and only took about 10 minutes. Code never returned. Fuel mileage and power increased a bit as well. That was about 4 years/60k miles ago and van is still running good with no o2 code. Tim

[boogieman]

doing some exhaust work, a while back when i replaced my O2 sensor i moved it from further down the pipe to the boss directly on the exhaust manifold...van has been running fine, but i will be having the exhaust redone from the manifold back and was wondering if this position is ok or i should replace the bung further down the pipe...are any of you running the O2 directly in the manifold?6829

[JPERL]

The 87 -89 AT 2WD/4WD Vans have the upstream(just one on the 87) 02 sensor further down on the pipe as shown. 88-89 have the upstream and down stream heated sensors 4 and 2 wire respectively) For some reason on the 84-87 van with MT the 02 sensor is mounted on the exhaust manifold . 84-86 Vans MT and AT have the 02 mounted on the exhaust manifold also

So I think you are fine to move it down

6840

[boogieman]

actually i want to keep it in the manifold if theres no bad reason to leave it...my collector pipe has seen better days and theres not much meat after the 02 bung for welding new pipe, so i was gonna have the exhaust guy start in front of the.bung..i guess i can add one later if issues arise..

[VanCo]

I've run both in the manifold and after on my 87 MT 4wd. I like in the manifold best. It allows the unheated o2 to heat up faster, and stay hot longer during idle. Other than the fact that it is more difficult to replace I have experienced no issues running the o2 in the maifold.

With the turbo I run a heated o2 pretty far back in the pipe now. I tapped the factory manifold blank to run an exhaust gas temp probe.

O2 bungs are cheap and easy for a muffler shop to install. You can order a bung and plug and have it welded in when you do the exhaust. That way you have options later on.

I should mention, I use the threaded style rather than the two bolt. They are cheaper and don't leak. There are two bolt to threaded adapters too.

[PearlVan]

Hi There, New member here. Been using the search function and familiarizing myself with this wonderful forum and our peculiar vans. Thanks in advance for the help.

Recent problem encountered:
I noticed that my Ox sensor was disconnected, however I did not get any codes when I jumped the check engine connector. I got the normal single blink every three seconds indicating all is well. Any ideas as to why a disconnected ox sensor would not throw a CEL code?

The second part to this story: The ox sensor wire that was broken was on the ECU side of the connector. I crimped a female spade on the wire and plugged it onto the male connector that is attached to the OX sensor. My question: is this just a single wire running from ox sensor to ECU or is there a ground connection made by the mesh wire shield?

[llamavan]

84/85 has a single wire.

It's common for the 1st gen vans to fail to throw an O2 sensor code even when the O2 sensor is not working, including when the wire is broken (been there). I don't know the reason; I only know it is so.

Gwen

[JPERL]

84/85 has a single wire.

It's common for the 1st gen vans to fail to throw an O2 sensor code even when the O2 sensor is not working, including when the wire is broken (been there). I don't know the reason; I only know it is so.

Gwen

the 2nd gen Van 86-87 also has a single wire with only 1 oxygen sensor. The 88-89 had (2) 02 sensors; the heated 02 sensors that were 4 wires for the upstream sensor and 2 wires for the downstream sensor