Carguy07 is spot on. Buy one Denso 234-9009 from a reputable seller, and replace the front sensor as it is the easiest to reach. See if that code goes away and the car runs ok. If so, buy a second Denso and repeat.

 

Also, buy a bluetooth code reader and get the torque app for your phone. This is mainly for android, although there are other options for iphone. You can monitor fuel trim to see if you are really running lean or rich, or any of a number of other sensors. And check and clear codes.
This one works well for me:

 

I have bought used sensors from ebay and none has worked. What happens is, the seller gets 100 of them from a junk yard or places unknown overseas and puts them up for sale. 50 of them may work fine. Of the 50 that don't work, 45 get returned (like yours). Those 45 go up for sale again, 40 come back. Up those 40 go for sale again, 35 come back.... eventually they all get sold. While it seems like you have a 50% chance of getting a good one the odds are actually very much against you because the bad ones appear for sale ten times as often as the good ones.

Here is how the odds work. Say one in a thousand motorists is a rapist-killer-psychopath. Your daughter's car breaks down on the highway. She is willing to take a 1 in 1,000 chance for a ride to town. Should she flag down the first car she sees or should she wait for someone to stop and pick her up? If you say the latter, you need to stop buying used sensors!

 

First, I don't buy used sensors. I only want to do a repair once,.My time is worth more than trying to cheap out on used parts. Plus, how long do you expect a used sensor to last anyway?

When I say buy from a reputable seller, I mean Amazon or Lexus dealers who sell on the internet at 30% off, or Advance Auto with a 30% off coupon.

For example, I just recently bought a Denso MAF for my RX from Advance auto for $90 + tax. Works perfectly and fixed the issue I was having.

 

I used to. Now I don't.

 

We got Denso 234-9009 Air Fuel sensors. About $150 each. Fixed the P1135 & P1155 codes.
Passed E-Check .On the way home CEL P0136 came on. Bank 1 Sensor 2. O well, back to some troubleshooting. :

Thanks for your help.

 

That one is a low priority that does not really effect how the car runs. Denso again on this one for around $50.

https://www.clublexus.com/forums/rx-...sor-2-diy.html

 

I just replaced the B1 S1 AF sensor, using Denso 234-9009. Followed the instructions here, and had a pretty easy time of it. I then pulled the fuse in the engine bay box to clear the CEL.


Previously, I was getting an intermittent code of P0172 (Bank 1 system too rich). Now, immediately after the changout, I have a "pending code" of P1150. This seems really weird. Do any of the vets here have any ideas why I would get a P1150 immediately after installing the B1 S1 sensor?

Edit: I just read on another site that battery voltage spikes can also trigger a P1150. Can anyone verify this? I definitely have been having battery problems.

 

Coincidence?

When was the B2S1 A/F sensor last changed? have you checked the fuel trims thru all of this?

 

Quick shout out to the OP for the terrific write up. I just recently changed out the B1S1 sensor. Ordered the part from A->Z for about $100 and spent about another $100 on various tools (ramps, wrenches, O2 sensor socket, and OBD 2 reader), but I was able to get it all done.

Hardest part for me was disconnecting the wiring connector. Fortunately I was able to reach up to the connector from the bottom. I pressed on the tab - it does take some effort - until I heard a click and release. At that point, it was easy to pull the connector apart. The sensor itself came out without any brake fluid or penetrant, just a breaker bar with a bit of pipe to extend it (granted, this car has been in Texas and California all its life).

Disconnecting the battery and pulling the fuse did not clear the CEL for me - I had to hook up the OBD 2 reader and clear it through that, but it did the trick. (The first OBD 2 reader I bought didn’t recognize the RX300 either, but that’s another story.)

 

Instead of PB Blaster, try using AeroKroil.

Works very well. Better than PB. I have no relationship with the company.