93 Land Cruiser O2 sensor location...FYI

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Sep 2, 2020
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Hi All,

I've searched all over to find out where the 02 sensors were located on my 93 TLC and finally found them. I wanted to quickly add it here, just in case someone else had a hard time finding them. They're side by side just before the cat and I'll be replacing them with these Bosch 02 Sensor replacements, as well as with this EGR valve, all from Rock Auto. Replacing them due to getting 'Check Engine' light and codes 28 - for 02 Sensor and 71 - for EGR system.

BOSCH 13448 Bosch Validated Oxygen Sensor
Upstream Right
BOSCH 13081 Bosch Validated Oxygen Sensor
Upstream Left
WVE 4F1673 {#226508, 2562066010, EGR4002} Includes Gasket

1. Does anyone know which one is Upstream Right and Upstream Left? Is it right or left standing in front or back of the TLC?
2. Does anyone have any opinions about the parts I've ordered?

I'm fairly new to working on my 93 TLC but experienced enough in working on cars, but hardly any tools to do major things.
1993 TLC 02 Sensor location_ExhaustMap.jpg

The attached Exhaust Map helped me to find out where the 02 sensors were, now I just need to know which is upstream right and left. :)

Thanks in advance!
 
We do not have upstream, downstream. We were 2 identical sensors in parallel. One of them has a longer wire and can be used in both position.

BOSCH is goats dong NTK is OEM 😂😂😂

Ok, will send the goats dongs back and order NTK's...👍🏽. Shalom!
 
I'm curious if that specific EGR valve will clear the CEL 71. I've got the same code on my '94 and from what I've researched, there are a variety of parts that can fail to trigger that code. I'm replacing the EGR vacuum switching valve (9091012079) to see if that fixes it.

Also, do you need to drop the cats out to replace the sensors?
 
I'm curious if that specific EGR valve will clear the CEL 71. I've got the same code on my '94 and from what I've researched, there are a variety of parts that can fail to trigger that code. I'm replacing the EGR vacuum switching valve (9091012079) to see if that fixes it.

Also, do you need to drop the cats out to replace the sensors?
Did you ever get this fixed with the EGR vacuum switching valve?

I'm not sure about dropping the cats. I just got all the parts today from Rock (will look at other places in the future too, not that I've run into any issues with Rock) and am going to try to replace today, even though it's 106 today. 🥵 I'll do that while I wait for my pulled pork to smoke :)
 
Oh, btw - anyone that has a 93 or 94 know if there are any gotchas or prep ideas when replacing the EGR valve or O2 sensors? Also, I'm assuming once these get replaced, the check engine should go away, provided there aren't any other issues. Meaning, there aren't any rain dances needing to be done to get the check engine light cleared. ;)
 
Oh, btw - anyone that has a 93 or 94 know if there are any gotchas or prep ideas when replacing the EGR valve or O2 sensors? Also, I'm assuming once these get replaced, the check engine should go away, provided there aren't any other issues. Meaning, there aren't any rain dances needing to be done to get the check engine light cleared. ;)

Even after replacing the sensors, you'll still need to clear the code from the ECM. All you need to do is remove the EFI fuse (15A) under the hood for at least 30 seconds.

I'm also still waiting on parts for the EGR code. Hows the rust around your cats/O2 sensors? Any tricks for removing them when they're really rusty?
 
Even after replacing the sensors, you'll still need to clear the code from the ECM. All you need to do is remove the EFI fuse (15A) under the hood for at least 30 seconds.

I'm also still waiting on parts for the EGR code. Hows the rust around your cats/O2 sensors? Any tricks for removing them when they're really rusty?
Thanks for the info on code clear on ECM. EFI is for Electronic Fuel Injection, suppose that this needs to be cleared to reset air/fuel mixture sensing?

Also, I was able to replace my inner O2 sensor with some mechanic yoga, which was the hardest one (think it would be Bank 2? Cyl 4-6?), but the outer one has one nut that appears to be stripped, meaning no sides, except for maybe a slight chance to get off. Any ideas welcome to get that one off. I may try that one this week or just go for the EGR valve replacement and then come back to that one. Ideas please...other than buying a small set of vise grips (hate to do, due to odds of worsening stripping nut), I've got nothing other than having my mechanic lift it and do it, but that costs more money. :-(
 
Thanks for the info on code clear on ECM. EFI is for Electronic Fuel Injection, suppose that this needs to be cleared to reset air/fuel mixture sensing?

Also, I was able to replace my inner O2 sensor with some mechanic yoga, which was the hardest one (think it would be Bank 2? Cyl 4-6?), but the outer one has one nut that appears to be stripped, meaning no sides, except for maybe a slight chance to get off. Any ideas welcome to get that one off. I may try that one this week or just go for the EGR valve replacement and then come back to that one. Ideas please...other than buying a small set of vise grips (hate to do, due to odds of worsening stripping nut), I've got nothing other than having my mechanic lift it and do it, but that costs more money. :-(
Oh, almost forgot to add, I used PB Blaster loosening agent (forgot the full name) and it worked great on loosening the nuts for the O2 sensor!
 
1. Does anyone know which one is Upstream Right and Upstream Left? Is it right or left standing in front or back of the TLC?

It's not germane to this discussion, but all left/right references in autospeak are from the perspective of sitting in the driver's seat.
 
It's not germane to this discussion, but all left/right references in autospeak are from the perspective of sitting in the driver's seat.
It's actually relevant and thanks for responding to my question in #13. So, from drivers seat, first O2 sensor to the right, would be bank 1 (Cyl 1-3) and the next right would be bank 2 (Cyl 4-6)?
 
It's actually relevant and thanks for responding to my question in #13. So, from drivers seat, first O2 sensor to the right, would be bank 1 (Cyl 1-3) and the next right would be bank 2 (Cyl 4-6)?
I don't understand 'first right, next right', and I don't see any diagrams in this thread that specify which side is bank 1-3 and which is 4-6, but whichever one is furthest over towards the (US spec) passenger side is right, and the one to the left of that, towards the (US spec) driver's side, is left. I would assume 1-3 would be furthest to the right (passenger side) but I'm not staring at my truck.
 
I don't understand 'first right, next right', and I don't see any diagrams in this thread that specify which side is bank 1-3 and which is 4-6, but whichever one is furthest over towards the (US spec) passenger side is right, and the one to the left of that, towards the (US spec) driver's side, is left. I would assume 1-3 would be furthest to the right (passenger side) but I'm not staring at my truck.
I was referencing your eluding to sitting in the drivers seat and discussing the O2 sensors by bank from left to right. Nevertheless, I've looked for a diagram such like one that I added in my original post, to see if these were labeled or had reference to the O2 sensors and bank specifications with Cyl numbers. It would be great if I had a reference like this for the exhaust. I will keep searching and post if I find one, unless someone already has one and provides it here. Thanks again!
 
If you look at the exhaust manifolds, 1-3 are the front one and 4-6 are the rear one. So I think the outboard is 1-3 and the inboard is 4-6. But it doesn't really matter, since you use the same oxygen sensor for both.

Also, I am lucky enough to not have smog BUT if you have EGR issues - check out HUDDEXPO's EGR kit. It just blends right in and cures your EGR woes. I did it as a preventative.
 
I'm curious if that specific EGR valve will clear the CEL 71. I've got the same code on my '94 and from what I've researched, there are a variety of parts that can fail to trigger that code. I'm replacing the EGR vacuum switching valve (9091012079) to see if that fixes it.

Also, do you need to drop the cats out to replace the sensors?

You do not. If you don't have to pass visual inspections where you are, I would highly recommend removing the PAIR system and placing the oxygen sensors in the PAIR manifold ports. MUCH easier to service.
 
You do not. If you don't have to pass visual inspections where you are, I would highly recommend removing the PAIR system and placing the oxygen sensors in the PAIR manifold ports. MUCH easier to service.
Not sure if this would work here in CA. I know my smog guy would probably look at it and move on, but not sure how that would affect smog cert as a whole.
 

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