How to replace a bank 1 sensor 1 oxygen sensor on a 1995 ES300 (w/ pics)
 

About a week or so ago my check engine light come on in the 1995 Lexus ES300 and when it was scanned, the bank 1 sensor 1 O2 sensor came back as bad. I decided to look up the part on Amazon and came up with this for a low $70:

http://www.amazon.com/gp/product/B000C5SGA4

The Bank 1 Sensor 1 O2 Sensor on this model Lexus is the one behind the engine, nearly against the firewall. It's not the front-most one and it's not the one past the catalytic converter under the vehicle on the exhaust. It's the toughest one to get to compared to those.

Knowing this, I thought about taking the car to someone and having them put it on but decided to do the work myself and learn something while saving a buckazoid or two.

The sensor came in today from Amazon and I went to my local parts shop and they happened to have O2 sensor sockets on sale for about $8 - not a bad start! I also bought a can of Blaster to help loosen the old sensor:

http://www.amazon.com/Blaster-16-PB-.../dp/B000I2079E

Here's the type of tool I bought to remove the sensor which worked great as it's flat and fits very, very easily into tight spaces:

http://www.google.com/products/catal...d=0CDsQ8gIwBA#

With these items in hand and the Lexus in the garage nice and cooled off, I got to work. Here's some pics.

Here's the tools and new sensor
http://www.andysp90x.com/Lexus/o2Pic1.jpg

The new O2 sensor came with some Locktite type compound (I hope that's what it was!)
http://www.andysp90x.com/Lexus/o2Pic2.jpg

Closeup of the tool used to remove the old sensor and tighten the new one
http://www.andysp90x.com/Lexus/o2Pic3.jpg

Ok.. Where is that B1S1 sensor? Let's start on the drivers side of the engine. Notice I placed my light there so it shines down on it while allowing me access on this side of the engine bay.
http://www.andysp90x.com/Lexus/o2Pic4.jpg

Creeping back behind the engine a bit now..
http://www.andysp90x.com/Lexus/o2Pic5.jpg

Look right behind the engine and in front of the firewall and thar she be. I've sprayed the Blaster stuff on it so it's shiny.
http://www.andysp90x.com/Lexus/o2Pic6.jpg

Up close and zoomed in.
http://www.andysp90x.com/Lexus/o2Pic7.jpg

Old one out, compared to the new one. I must say.. This was actually quite easy to remove. I simply slid the tool/socket over the old O2 sensor, attached a ratchet to it and with one tug, it broke loose. I then pulled the tool/ratchet out, unplugged the harness cable (just press the ribbed clip and pull apart), and then hand-loosened the old sensor the rest of the way until it was out. When I got it out I did a small "YEAAHHHH!!" celebration while shaking it and staring at it with crazy eyes and then went back to work.
http://www.andysp90x.com/Lexus/o2Pic8.jpg

Dirty as heck. I bet this is the original sensor from 1995.
http://www.andysp90x.com/Lexus/o2Pic9.jpg

I put the locktite paste on the new sensor threads, carefully, slowly lowered the new sensor through the cavity there behind the engine and into the hole it belonged and then hand tightened it into place. Reattached the cable harness and then used the tool/ratchet to make sure it was all tight and was done.
http://www.andysp90x.com/Lexus/o2Pic10.jpg


Overall, despite it being in a fairly rough place to get to, it was a very easy replacement. Couldn't have gone smoother and I think it took me 20 minutes tops to handle it all. It took me longer to make this post.

That went so easily, I'm wanting to change out the front O2 sensor just for the fun of it. Thanks for reading and I hope this helps someone in some way.

Nice write-up! That looks like copper based anti-seize compound.

Wow! $8 dollars for an O2 sensor. What else was your local parts shop giving away?

I wish! It was the socket on sale not the sensor, sorry for the confusion. The sensor was $70 through amazon.

Oriellys isn't that cheap. ;D

Great job, Andy! No more CEL? (due to P0135 code, I guess)

Not showing so far but I've only put maybe 20 miles on it since the change. I'm thinking of making it to a meet tonight that's about 60 miles away or so and we'll see how it goes.

God, I do not miss that TX dirt....

Yeah the dust and dirt here sucks especially where I live. To keep it clean would mean a daily wash and window clean.

Good write up..I have to change bank 1 sensor 1 & 2

thank you .dis is helpful

Excellent write-up! This should definitely be added to the Official ES HALL of FAME links thread at the top of the ES300/ES330 forum page! Thanks for posting! :thumbup:

Good work nice ( did u have 2 clear code after? )
 

Good work nice ( did u have 2 clear code after)

es300 1999
 

I happened to run across this thread and seen were you replaced this sensor.My car is throwing code 1135 and 1155.Which is supposingly the af sensor not the 02 sensor.Could you tell me or show me a diagram of the location of this af sensor?

hey man, great post!

I'm just curious how were you able to figure out the original denso part number? I went to the store and they gave me a air/fuel sensor which I now know is wrong. I tried looking up OE parts and I just get these obscure numbers from websites wanting to sell it themselves.

You totally took care of this issue, but I'm trying to understand how to solve my own issues in the future.

thanks!

Hi I have un connected the eletrical connector for b1s1 sensor, but have trouble to remove the nut, is counter clockwise to remove it? tried with different liq like deep creep, pb blaster, and even try to start the car for 10 min. still doenst work, any idea?

Thanks