D.I.Y. Oxygen Sensor Replacement
 

Hey guys. I own a 2001 Gs300 with 64K miles and I just recently had my check engine light
come on so I took it to the Lexus dealership. They ran a diagnostic test and found the one of my oxygen sensors was out. The Bank 2 Sensor 2 sensor to be exact. I then asked how much for the part and labor
and was quoted $400 here in Houston. I found it hard to believe it could be that expensive and that hard
to do. I found the part on oxygensensors.com to be the cheapest @ $110 with shipping and the
oxygen sensor removal tool. This job took about 30 minutes to complete. This is how I was able to change the sensor so here it goes:

1) Locate sensor (this one is for the Bank 2 Sensor 2)
2) Raise car - i used a floor jack and lifted up the front passenger side and put a stand under the front suspension just in case the jack fell.
3) Spray some lubricant around connection of sensor, I used WD-40, to help loosen.
4) Using the oxygen sensor removal socket I then loosened the bad sensor and removed it completely from original position.
5) I then lowered the car in order to follow the sensor cable inside the car under the passenger floorboard carpet.
6) First remove plastic piece on passenger side door railing.
7) Then I pulled the carpet back just far enough to see where the O2 sensor came into the car and where it was connected. It feels like the carpet doesn't want to go the way you want it too, like it won't go back into position but it all goes back just how it was very easily. Don't worry. Just don't force anything too hard.
8) Disconnect sensor from plug. Pull gasket from floor board that is keeping it air and water tight around wiring.
9) Wrap tape, I used painters tape, around new sensor in order to protect it from hitting the ground as you feed the new sensor through the floor board. I was told these sensors are very delicate and you don't want them slapping the pavement as you feed it through the floor. Don't hook the wire harness up yet. You have to twist the sensor back into place so if the connect the wire harness you twist the wires pretty badly.
10) Raise car back into place.
11) Put the seize-all that is provided with sensor on the threads.
12) Screw sensor back into original position. Careful not to cross thread. You have to have it lined up just right for it to screw on just right.
13) Lower car.
14) Connect wire harness back.
15) Put gasket back into original position.
16) Put carpet back into original position
17) Put plastic door molding back.
18) I then disconnected the negative terminal from the battery in order to reset ECU. Waited 30 min.
19) Reconnect terminal and you are done.

Not a very hard job at all and I am no where close to being a mechanic. I just couldn't see spending that much on just an O2 sensor. Hope this helps.

Pics of Sensor Replacement
 

Pic 1 is the oxygen sensor removal tool.
Pic 2 is the location of sensor under car
Pic 3 is the location of sensor under car close up
Pic 4 is the location inside car under passenger side carpet
Pic 5 is the location inside car under passenger side carpet close up
Pic 6 is the wire harness connection close up
Pic 7 is sensor wrapped in tape.

Pic2
 

Havent figured out how to post mult. pics. sorry

pic3
 

Pic3

pic 4
 

pic 4

Pic 5
 

Pic 5

pic 6
 

pic 6

pic 7
 

pic 7

this is awesome, thanks for all the instructions

Awsome Post.
Worthy of a Sticky!

definitley sticky worthy

very very valuable info

nice job on post and pics

Excellent Job BVance. 18 posts and you come up with this eternal winner. You rock!


My TPS is going out, so I'm in similar pricing and labor as you were. I'll be making a similar thread when I replace it.

Just called Keyes Lexus and they want $700 for this job. I guess i will try this DIY after all.... and put the rest of the saving to my son's 529 plan!!!!

Generally a screw in type sensor like that would be a 7/8 open end wrench if you don't have the O2 socket. Mine is a first gen and still has the two 6m bolts holding it in.

Caution Ordering Oxygen Sensors Form Oxygensensors.com

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The part numbers for the oxygen sensors for 99-00 GS300 on oxygensensors.com are incorrect. I ordered oxygen sensors for bank 1 sensors 1 and 2. Each costing 100+ dollars. I installed bank 1 sensor 1 and took my GS to Lexus to have the EUC reset and to make sure that was the only problem making my check engine light come on. I was told that the sensor I installed was not working correctly. I wasnt sure if they were telling me the truth since I didnt buy the sensor from Lexus. You know how that goes. I was also told that I needed to replace bank 1 sensor 2. I ordered that sensor from oxygensensors.com as well. I recived it today and went to install it and noticed that the numbers on the sensor didnt match the one I had just taken off my car. I did a search on google to see if these numbers checked out or cross refernced but instead I found a thread on CL where other people were having the same problem I'm having getting the wrong sensors from oxygensensors.com. I called up oxygensensors.com and was questioned as to weather or not I knew what I was doing. I worked on cars for a living longer than oxygensensos.com has been around. I told him that the numbers on the sensor its self did not match up. He told me that the numbers on the sensor had nothing to do with a part number, that they were just a referance as to where they were made. I know better than that so I looked up the numbers on Denso's website and found the correct part numbers. I hope I get this all straightened out. I already put one of the sensors on the car so so much for getting that money back or exchanging the part. Now I see why there sensors are so cheap. You end up paying 200+ anyway....

the correct Denso part numbers are:

(1,2,3 precat) Bank 1 Sensor 1: 234-4048

(1,2,3 postcat) Bank 1 Sensor 2: 234-4626

(4,5,6 precat) Bank 2 Sensor 1: 234-4630

(4,5,6 postcat) Bank 2 Sensor 2: 234-4603


oxygensensors.com has part numbers

(1,2,3 precat) Bank 1 Sensor 1: 234-4048

(1,2,3 postcat) Bank 1 Sensor 2: 234-4622

(4,5,6 precat) Bank 2 Sensor 1: 234-4626

(4,5,6 postcat) Bank 2 Sensor 2: 234-4603