timmui

I don't either, but since I am not having issues with that sensor, I wasn't going to try looking for it. However, while crawling under my RX today doing a caliper swap, I took some pictures and one of them shows the wiring for the O2 sensor at the bottom, clearly on the driver's side of the vehicle.

I think I'm chalking it up to a typo that wasn't caught.

Rudy602

I've noticed that a lot of service manuals have inaccuracies or leave out pertinent information. You'd think that if you pay considerable money for an alleged "factory" service manual, you'd get good info. but that isn't always the case. Who knows what gets lost in translation and editing - esp. by those who aren't mechanics.

salimshah

I simply refer to the one under driver-seat as downstream sensor.

Salim

timmui

I used to work for a US distributor of a Japanese precision equipment company and the literal translations were often amusing if not downright confusing. It's because of this job that I feel so comfortable tinkering with my Japanese designed vehicle. The parts diagrams look very similar. I swear that some of their mechies must have gone to the same engineering school!

Though I don't ever think they mistook left from right on any of their parts manuals. Easier to do if you have to manufacture right hand drive cars and trucks, I guess.

Rudy602

So do I - but a lot of manuals don't and this can lead to confusion, esp. with DIYs who have less understanding of the function and process involved and even more so if the manual says it is located under the passenger seat. It's nice to have this forum for the great info, pics, and clarification.

LexVoitek

Hey,

I just found this thread and noticed that the procedure to replace an o2 sensor on a first generation Lexus RX is almost completely the same as on my 2006 Lexus GS 300 AWD.

I actually went the extra mile and recorded the entire process. I'm sure it will help anyone attempting to do this on any Lexus with the exception of the Lexus LFA supercar

BTW: I have several Lexus road testing clips, races, and service and repair videos on my YouTube Channel already, with a ridiculous amount of videos still waiting to be edited.

Here's my Lexus o2 Sensor Replacement Tutorial

sarah

I replaced the A/F mixture sensor under the engine last year. Last week and CEL
came on again and showed that the other A/F mixture sensor near the manifold is
bad. So I opened the hood and replaced it with the Denso sensor. It only took me
2 minutes with my oxygen sensor tool and wrench. (because I had soaked it with
PB Blaster for 30 minutes to loosen it up)

The only sensor that I've never replaced is the oxygen sensor on the exhaust,
under the driver's seat. That sensor is the one that came with the car and has
never ever been replaced. I figure I might as well do it now. The Denso sensor
for that one is only $50 on Amazon.

Is it absolutely necessary to remove the driver's seat for this one? The carpet
under the seat has been pre-cut from the factory. When I reached in there with
my fingers, I felt the wire/connector of the oxygen sensor. What if I just make the
cut bigger? My carpet is black, so it will not be visible.

Thanks!

Rudy602

It can be done either way. You can remove the seat and have more room to work - I moved the seat as far forward as it would go and cut the carpet a little.

Nick26

The left side is the driver's side in the U.S., but is the passenger side in Japan. Same location, failure to convert!

salimshah

I saw this today and may be a bit late in responding:
You have to make sure that the plug can pass through the carpet and the grommet on the floor. At the factory the grommet was installed before the carpet so a tiny hole to pass the plug was enough. If you are going to work with the seat insitu then you mostlikely will have to cut the carpet hole a bit bigger. If you remove the seat you can potentially work with a smaller hole. At the end the carpet will be covered by the seat and you can use a thread and a needle to mend the cut.

Preemptively changing the sensor .... I am not in favor of that. If it is a maintenance item, yes, if not then wait for it to cause a CEL.

Salim

Rudy602

If my memory is correct, nothing needs to go through the hole in the carpet except your fingers in order to unplug the old sensor connector and then reconnect the new one. The connector is then removed and replaced through the floor from below through the hole plugged by the grommet.

ssgi4in12

Thanks lexmex for your detailed guide. However since I have been getting the P0420 error code, I was strongly thinking of fooling the ecu by using a spacer. I bought the spacer but I am unable to use it. Is it possible for me to use the spacer on this type of sensor? See a pic of the exact spacer I got This is the blox spacer

MIKEY19625

Hello

I'm getting code P0037 Oxygen sensor Heater Control Circuit Low (Bank 1 Sensor 2). I've called two Lexus Dealers and i've gotten two different part numbers. Does anybody have any idea for the right part number and location of this sensor? I accept an aftermarket part# as well. I will appreciate the heads up.

thank you,

Mikey

Doug079

Hi all, firstly many thanks to all who contribute and make this a 'gold mine' of information for Lexus owners.

I am attempting to refit an oxygen sensor to the exhaust of my Lexus year 2000 RX3000 AWD.
Yesterday the VSC and CEL lights illuminated and I started my research ultimately leading me here. Reading the most common codes this throws up and what they refer to (being based in the U.K. I don't have access to any free code reading ) I decided to check the obvious visuals, loose connections from the air filter, all good there. Then I read of the 02 sensor on the exhaust and remember a small putt putting from the exhaust.... Low and behold there were no nuts on the bolts holding the sensor and shield in place!
understandably the shield and sensor were loose, just hanging in place. The threads weren't in very good shape and the gasket just disintegrated. I used WD 40 on the threads and a wire brush, it helped as the replacement Nylon lock nuts would not thread prior to this and even then I had to use 2 nuts in a socket so as to apply enough pressure just to get the nuts to thread. 4 quarter turns clock wise and then 4 anti clock wise at a time, generous amounts of WD 40 sprayed after each 4 anti turns I managed to get the nuts back on. I was under pressure as we use the car to transport our kids to school a couple of miles away and it was raining! And I didn't want the sensor bouncing on the tarmac or being ripped off.
Anyway my questions are, are the nylon lock nuts acceptable for this application?
Im still searching for a replacement gasket, the only one I found P.N 89466-20020-83 is located in the U.S, shipping time 21 days. Could I make a gasket from high temp 250c 1.5mm gasket paper or exhaust sealer/liquid gasket?

carguy07

I would think nylon nuts would get cooked. Mine did the same thing, I just used old school lock washers. You could run it without a gasket for a long time, but they have to have those local for you. Look for Dorman part # 47021. The gasket is a very universal part that fits tons of cars.