Sabio755

Good day day to you Sir/Mam;

After a steady yellow check engine light, reading the code and doing a resistance check on the sensors, I have confirmed the need to replace an O2/Fuel air sensor on my 1999 Lexus RX 300 AWD.

The faulty sensor is the first one you see when you open the hood, I think it is called bank 1 sensor 1 pre cat sensor.

I read the advices on this forum's many posts and I heeded the warnings. I will stick with the OEM DENSO sensors.

Here is my problem... After reading on the DENSO sensors it seems that both PN 234 9009 and PN 234 4215 can be used to replace the sensor.

http://www.onlinewholesaleparts.com/toos-117.html
http://www.onlinewholesaleparts.com/toos-221.html

PN 234 9009 seems to be more RX 300 specific and can be bought for around $120, while PN 234 4215 seems to be design for a broad group of Lexus and Toyota, including my 99 RX 300. This sensor only sells for $57.

Are they any risks, performance losses or inconveniences using the PN 234 4215 instead of the more specific PN 234 9009?

Did any of you ever used PN 234 4215? What were your impressions?

Thank you for your time,

Regards,

Sabio755

ecoastkid

according to the rock auto website, 2344215 is the downstream sensor ( meaning after the cat) so you do not want to use that one.

Btw..rock auto as the 2349009 for 99.79 (But I dont know the shipping cost)

Sabio755

@ ecoastkid

Thank you so much for your prompt reply. onlinewholesaleparts.com and the amazon link that I was following were both showing the picture of a sensor without the flange you always see for the downstream sensor. Without descriptions, I assumed PN 234 4215 that it had to be for the upstream sensors...

Well I am shame to say that I was way out to lunch with this one.

Thank you for setting me on the right path.

Topic close (^_^)

Sabio755

ecoastkid

Glad I could help. I just got lucky that rockauto had a good description.


BTW...Tell me about how you did your testing of the sensor.

Thanks,
Dave

Sabio755

@ecoastkid

For the testing, I used an ODB2 tool that read an error code for Bank 1. I knew Bank one had 2 sensors, so I simply unplug one sensor at the time and look at the OBD2 tool to see if any changes. Once I was pretty certain that it was sensor one, I used a multimeter to check the circuits resistance in the sensor. Mine have no resistance showing, basically a broken circuit. I know there is a spec for the resistance you are expected to have (maybe 0.8 to 1.2 ohms, guess) but like I said mine had none.

The most difficult thing for me to do was to unplug the damn sensor...

I am no mechanic, I just used my head and hopefully I am right. The final test will be when I replace the sensor.

Hope this answer your question.

Regards,

Sabio755

ecoastkid

Yes that anwsered it. Thanks...

I've never bothered to check the resistance of the o2 sensors as I just replace if I suspect it. I think I might do that next time though.

carguy07

"The faulty sensor is the first one you see when you open the hood, I think it is called bank 1 sensor 1 pre cat sensor."

That is actually Bank 2.

https://www.clublexus.com/forums/rx-...el-sensor.html

https://www.clublexus.com/forums/rx-...esistance.html

code58

The FRONT sensor is indeed Bank 2, Sensor 1. Sabio wouldn't be the 1st one to replace the wrong sensor because he had misidentified the banks. Bank 1, Sensor 1 is back by the firewall.

ecoastkid

So he is getting the right kind of sensor but just replacing the one on the wrong side of the motor?

Personally, I would just replace them all..haha. How many are there? 3 or 4?

carguy07

Two air fuel, one oxygen sensor. The air fuel sensors seem to die regularly, oxygen sensor not so much.

https://www.clublexus.com/forums/att...sensor-1-3.pdf

code58

Well, if he gets the 234-9009 sensor he's getting the right one. He originally was wondering about getting the cheaper sensor which is an 02 sensor and is behind the C.C. and that would be the wrong one. He was confused about which was Bank 1 and Bank 2.

Sabio755

Hello all,

I just wanted to pop up and do a proper closure on this post.

First of all, thank you all for your information and assistance. This forum is extremely useful and filled with friendly users willing to lay a hand when needed. Awesome community!

Now for the meat and potatoes...

I had a garage looked at my error code and told me it was the front sensor. He had called it bank 1 sensor 1... I bought a replacing Denso 234-9009 from eBay a just under $100. That sensor is the same part number for both pre cat F/A sensors.

I do not always trust mechanics, so I did my own tests.

I disconnected the front one and did a ohms resistance on the sensor. It read 0.00

I then disconnected the other sensor (the one colse to the firewall) and conducted a resistance check on it. That one read 1.2 on my voltmeter settings. When I received the new sensor 234-9009 from the mail, I did one last resistance check and got another 1.2 ohms...

That was my final confirmation check that the front F/A sensor AKA bank 2 sensor 1 was the faulty one. I replaced it, cleared my check engine light and been driving 2 weeks without further problems...

The only problem I ever got was how frustrating and difficult it is to disconnect the Bank 1 sensor 1 close to the firewall!!!

Again, thank you all for your help.

No offense, but I hope I wont need you anytime soon...

Regards,

Sabio755

artbuc

AMEN BROTHER!!! I did a lot of work on my RX including TB, A/C condenser and struts. However, no job was even remotely as difficult as disconnecting that B1 freakin' A/F connector. I can say the same for my 99 Avalon which has the same engine. I tell people to practice disconnecting B2 but even when you know the magic spot to squeeze it is still hard.