What's interesting is your light seems to stay off for a while right?
Even if I pull and clean all plugs + use compressed air my light comes back on within 50 miles. I'm beginning to wonder if the sensors are just bad now and do need replaced
oil wicking up my o2 sensor wire harness?
- Thread starter turbo sol
- Start date
What's interesting is your light seems to stay off for a while right?
Even if I pull and clean all plugs + use compressed air my light comes back on within 50 miles. I'm beginning to wonder if the sensors are just bad now and do need replaced
do all your lights stay on?
If I don't do the zero point recalibration, I can clear the engine lights, but not the VSC lights. - from what I read, this is because I have an early model year with slightly different OBD initialization.
I figure anything over 100,000 has seen better days (02 sensors in particular)
If I don't do the zero point recalibration, I can clear the engine lights, but not the VSC lights. - from what I read, this is because I have an early model year with slightly different OBD initialization.
I figure anything over 100,000 has seen better days (02 sensors in particular)
Ya they do stay on... The vsc lights come on with the check light. I'll do the zero point....never done it before.
I think my next step is to replace both upstream sensors since they have never been changed. Any tips for changing those?
for me, the hardest part was unplugging them.
make sure you use a 02 socket, and since its going to be replaced… look at some PB blaster a day or 2 before you tackle it.
also make sure you use anti-seize on the new ones. (most come with it preplaced on the threads.)
I've replaced all the 02 sensors in mine. 187,XXX
for me, the hardest part was unplugging them.
make sure you use a 02 socket, and since its going to be replaced… look at some PB blaster a day or 2 before you tackle it.
also make sure you use anti-seize on the new ones. (most come with it preplaced on the threads.)
I've replaced all the 02 sensors in mine. 187,XXX
OK thanks! You aren't kidding about the connector... I've read that many times in different 02 threads lol. I looked last night and can barely get my hand where it is. I'm going to try to replace both fronts over the holidays.
i've been longing to replace the upstream sensor on my v6, i just could not find a way to remove it. i have no leverage.
Sent from my SM-G930T using Tapatalk
gm350reratliff
New member
I’m eating crow today.
A couple pages back I spoke about my friend’s super clean FJ that had thrown a bank 2 lean code and a A/F sensor slow switching code. The dealership said they found transmission fluid in the harness at all the O2 sensors and at the ECM. They wanted over 5k to fix it but they never mentioned how they would prevent this from happening again. My friend and I were pretty suspicious with their diagnosis so he told them to just put it back together and picked it up. We cleaned the MAF, since the first and only check engine light was caused by them leaving the air filter lid and air filter completely off. I also pulled apart a couple transmission connectors and rear O2 sensor connectors but they were completely dry.
That FJ was running perfect until last week when the CEL came back on. The FJ was running smooth but the gas mileage had really gone down. He brought it to my house for me to look at and finally this week I had a chance to check it out. Hooked it up to TIS and found a p0171 bank 2 lean code like before. I also noticed the #2 long fuel trim was in the 30s. Thinking along the lines of the MAF still dirty, I cleaned it but that didn’t help. I swapped the MAF with the one from my 4th gen, that wasn’t it either. I finally pulled the bank 2 A/F sensor and much to my surprise, there was a little bit of oil in the connector. I pulled the other A/F sensor and found oil in that connector as well. I swapped the sensors from side to side and took it for a test drive. The lean code followed the sensor but it also triggered a A/F sensor heater circuit open code. I pulled that sensor and checked for continuity across the heater circuit and found it open. I swapped in a A/F sensor from my 4th gen and the FJ runs great with no codes. Cool, a new A/F sensor will fix the codes (hopefully) but where is the oil coming from?
I pulled apart the transmission control connector and found the source of the oil. This connector has a bunch of oil in it, definitely transmission fluid. So, it appears the dealership was, partially, right. I haven’t checked the ECM yet, hoping to tomorrow, and I still need to check if the transmission vent is actually plugged. I’m doubting that the vent is actually plugged since this FJ is pretty clean and pampered. My friend needs the FJ back so I’m installing a new sensor and hoping for the best. In the meantime I’ll research what is needed to correct the problem. For the hell of it, I popped off the trans control connector on my 4th gen and unfortunately found a little bit of oil in there as well. It doesn’t seem to be near as bad as my friend’s FJ but it’ll probably get there over time. Now to prove that no good deed goes unpunished, I went to re-install the A/F sensor back into my 4th gen but I noticed there was a little oil inside the connector so I sprayed it out with electrical contact cleaner and blew it out with compressed air. Now I’m getting an A/F sensor heater circuit open code on my 4th gen. Pulled the sensor and sure enough, the heater circuit is open. So either moving the sensors around (I was pretty careful with them) messed them up or the contact cleaner in the connector somehow fried the sensor. Either way, looks like I’ll need one as well.
So now, I’m a believer in this problem. With all the FJs, Tacomas and 4runners out there, I can’t believe we don’t hear of this problem more. So does anyone know what I need to fix both the FJ and my 4runner? I’m thinking the FJ will need the transmission connector and wiring harness at least. My 4runner will probably just need the connector on the transmission. Here’s some pictures.
A couple pages back I spoke about my friend’s super clean FJ that had thrown a bank 2 lean code and a A/F sensor slow switching code. The dealership said they found transmission fluid in the harness at all the O2 sensors and at the ECM. They wanted over 5k to fix it but they never mentioned how they would prevent this from happening again. My friend and I were pretty suspicious with their diagnosis so he told them to just put it back together and picked it up. We cleaned the MAF, since the first and only check engine light was caused by them leaving the air filter lid and air filter completely off. I also pulled apart a couple transmission connectors and rear O2 sensor connectors but they were completely dry.
That FJ was running perfect until last week when the CEL came back on. The FJ was running smooth but the gas mileage had really gone down. He brought it to my house for me to look at and finally this week I had a chance to check it out. Hooked it up to TIS and found a p0171 bank 2 lean code like before. I also noticed the #2 long fuel trim was in the 30s. Thinking along the lines of the MAF still dirty, I cleaned it but that didn’t help. I swapped the MAF with the one from my 4th gen, that wasn’t it either. I finally pulled the bank 2 A/F sensor and much to my surprise, there was a little bit of oil in the connector. I pulled the other A/F sensor and found oil in that connector as well. I swapped the sensors from side to side and took it for a test drive. The lean code followed the sensor but it also triggered a A/F sensor heater circuit open code. I pulled that sensor and checked for continuity across the heater circuit and found it open. I swapped in a A/F sensor from my 4th gen and the FJ runs great with no codes. Cool, a new A/F sensor will fix the codes (hopefully) but where is the oil coming from?
I pulled apart the transmission control connector and found the source of the oil. This connector has a bunch of oil in it, definitely transmission fluid. So, it appears the dealership was, partially, right. I haven’t checked the ECM yet, hoping to tomorrow, and I still need to check if the transmission vent is actually plugged. I’m doubting that the vent is actually plugged since this FJ is pretty clean and pampered. My friend needs the FJ back so I’m installing a new sensor and hoping for the best. In the meantime I’ll research what is needed to correct the problem. For the hell of it, I popped off the trans control connector on my 4th gen and unfortunately found a little bit of oil in there as well. It doesn’t seem to be near as bad as my friend’s FJ but it’ll probably get there over time. Now to prove that no good deed goes unpunished, I went to re-install the A/F sensor back into my 4th gen but I noticed there was a little oil inside the connector so I sprayed it out with electrical contact cleaner and blew it out with compressed air. Now I’m getting an A/F sensor heater circuit open code on my 4th gen. Pulled the sensor and sure enough, the heater circuit is open. So either moving the sensors around (I was pretty careful with them) messed them up or the contact cleaner in the connector somehow fried the sensor. Either way, looks like I’ll need one as well.
So now, I’m a believer in this problem. With all the FJs, Tacomas and 4runners out there, I can’t believe we don’t hear of this problem more. So does anyone know what I need to fix both the FJ and my 4runner? I’m thinking the FJ will need the transmission connector and wiring harness at least. My 4runner will probably just need the connector on the transmission. Here’s some pictures.
gm350reratliff
New member
[MENTION=66389]BlackWorksInc[/MENTION]
What is needed to fix the transmission electrical bulkhead from pushing fluid through the harness? I’m guessing the FJ will need a new harness as well.
What is needed to fix the transmission electrical bulkhead from pushing fluid through the harness? I’m guessing the FJ will need a new harness as well.
Supersonic
New member
This quote is from page 2. You might not need the entire harness according to this solution;
https://www.justanswer.com/toyota/6xjis-toyota-4runner-sr5-2003-4runner-chronic.html
https://www.justanswer.com/toyota/6xjis-toyota-4runner-sr5-2003-4runner-chronic.html
gm350reratliff
New member
Thanks. I may give that a try. I would like to at least fix the leak at the transmission connector so no more fluid gets pushed through the harness. On the FJ, even the harness inside the vehicle at the ecm is wet. Maybe splice in solid wire on every single wire from that transmission connector and the A/F sensor wires.
Supersonic
New member
The way I would try it is to block all the wires coming from the transmission by splicing into a section near the transmission. Then I would clean the other connectors as necessary to eliminate the fluid in the hopes of not having to replace the harness. Disclaimer here is that I don't have experience doing this kind of repair and I am thinking the cost and time of replacing the wire harness may be expensive.
Where is the transmission connector located on the transmission that you found fluid in? I need to check mine. I'd say the logic sounds right with splicing solid wire at this connector. I'm replacing both of my upstream 02s/AF this weekend. My gas mileage really tanked once the p2238 code came on.
gm350reratliff
New member
The connector is on the driver side of the transmission, just above the pan, behind the shift cable bracket. This is on the A750F, not sure if yours will be in the same location.
The fix that the dealer ship told me was to replace the internal wiring harness for the transmission.
(dropping pan, and who knows what other little parts)
they also wanted to change the ECU, but i would hope the new wiring harness would fix it.
I don't know of a superceded part number (indicating something had been fixed to prevent the issue from happening again…) so I don't know how long the new harness will help for.
maybe this part?
Toyota 82125-60650 Internal Wire Harness Replacement
Some instructions
http://ww2.justanswer.com/uploads/Hipo64/2012-07-28_232315_ace_-_44.pdf
based on this post
https://www.justanswer.com/toyota/6xjis-toyota-4runner-sr5-2003-4runner-chronic.html
(dropping pan, and who knows what other little parts)
they also wanted to change the ECU, but i would hope the new wiring harness would fix it.
I don't know of a superceded part number (indicating something had been fixed to prevent the issue from happening again…) so I don't know how long the new harness will help for.
maybe this part?
Toyota 82125-60650 Internal Wire Harness Replacement
Some instructions
http://ww2.justanswer.com/uploads/Hipo64/2012-07-28_232315_ace_-_44.pdf
based on this post
https://www.justanswer.com/toyota/6xjis-toyota-4runner-sr5-2003-4runner-chronic.html
you know were not alone when its
#6 on car complaints
https://www.carcomplaints.com/Toyota/4Runner/2003/electrical/electrical_system.shtml
#6 on car complaints
https://www.carcomplaints.com/Toyota/4Runner/2003/electrical/electrical_system.shtml
gm350reratliff
New member
Thanks! That internal trans harness looks to be the right one and the root of the problem. I may just splice in some solid wire like others have done and hope for the best.
I was thinking of buying or making some short O2 sensor plug extensions that have the solid wire in them so at least that part would be plug and play.
I replaced the upstream bank 1 sensor today. Once I got the harness unplugged, and the right socket it was a relatively easy job. Light has been off for the 10 miles I drove it so far. Just filled up with gas....14.19 mpg ..yikes. I'm guess the new sensor should help. The old one was caked in carbon. The plug was saturated with oil. I did clean it the best I could.
I'm planning to do bank 2 upstream next week.
I'm planning to do bank 2 upstream next week.
AuSeeker
Elite Member
While yes the wicking problem is an issue with 4th Gens but to say it's the #6 electrical issue with 4th Gens is not accurate considering the evidence you posted, the "#6" you're referring too is the just the 6th posted electrical complaint posted on that website, which was posted by just one person, and not the overall #6 electrical complaints from ALL 4th Gen owners.
[MENTION=149207]AuSeeker[/MENTION]
I know it's not the number 6 issue for all 4th gen owners. Just like the #1 issue listed, isn't the top issue for 4th gen.
I was mearly calling out the number associated with our issue on that page for those checking it out.
To me – it helps to know there are more and more people out there with this issue, the troubling part is that Toyota seems uneducated on the issue, or wanting to own up to the faulty engineering of the their setup.
I wonder how many misdiagnosed issues around CEL and 02 sensors have been really a product of the transmission fluid wicking through the harness.
I know it's not the number 6 issue for all 4th gen owners. Just like the #1 issue listed, isn't the top issue for 4th gen.
I was mearly calling out the number associated with our issue on that page for those checking it out.
To me – it helps to know there are more and more people out there with this issue, the troubling part is that Toyota seems uneducated on the issue, or wanting to own up to the faulty engineering of the their setup.
I wonder how many misdiagnosed issues around CEL and 02 sensors have been really a product of the transmission fluid wicking through the harness.
gm350reratliff
New member
My thoughts as well.
Mercedes has a similar problem with the engine oil getting pushed into the harness from the cam sensor or valve timing plugs. At least Mercedes did the right thing and issued a recall on the issue.
Similar threads
