I haven't replaced it yet. If the code returns, I will replace it with the Denso OE Part# 234-4805 for $133 from Parts Plus. Here's the site: http://www.densoaftermarket.com/cata....php?part=o2sn

What did you do to make the code go away? I thought you needed to change the O2 sensor. IF you turned off using the diagnostic tool, it will come back soon. I found a cheaper website http://www.rockauto.com/catalog/raframecatalog.php. The cost $106.79. Is there a reason you would wanna use Denso and not Bosch? The Bosch #13355 one is $87.

Good to know... I'm in the process of replacing my 3rd O2 sensor on my truck in 5 years. Toyota did the first two, I will be doing this one. $400 for the sensor plus $95 for the code diagnosis... So much for low ownership costs!

I got the OE oxygen sensor. Brand was Standard Part SG38 for $86. I tried replacing the sensor yesterday and it seemed impossible to loosen the sensor from under the truck. DO I have to lift it up the truck to get a better handle of it? I wanted to replace it myself and save money. Anyone had trouble loosening the old O2 sensor?

Spray a little WD-40 and let it sit for several minutes.

I did spray WD-40 on it.. still very very tight....

If WD40 didn't do it, you may need to find something that is more of a penetrating lube instead of just a lube (like WD40). Look for any products that advert themselves as "penetrating" and let that sit in it a while. Should eventually loosen it up.

Also, this is why it is absolutely MANDATORY that you apply anti-seize grease on the new sensor's threads before you install it. Most parts houses (AutoZone, Advance, O'Reilllys, etc) sell anti-seize grease in single use portions near their registers today. If not, a little tube will last you for a while and isn't much $$.

Also, having looked at the diagrams provided, I agree with the idea that Bank 1 on your engine is passenger side. I only mention that you will need to forget that if you ever get the 4.7L V8 - the banks are reversed in those engines and Bank 1 is driver's side and Bank 2 is passenger side. I know this from putting about 6 'Bank 2 Sensor 2' sensors in my Tundra for about the last 9 years now (having owned it 10 years this month). Toyota did the first 3, I've done the last 3. Find the parts online, buy a tube of anti-seize and you won't have to drop $400-$500 at the dealership to get it done. About $100 for the sensor and about 5 minutes under the truck should knock it out. Buying a code reader (that can also clear CELs) and finding a good source for O2 sensors was the best investment I ever made in my Tundra...those sensors have been my only real issue with it over 10 years and 150k miles.

Thanks for the input guys. Had same problem with the VSC TRAC, TRAC OFF, and CEL lights lighting up in my 2004 4Runner Sport Edition. Took it to Autozone to get the free problem code service and they said code was PO135, Bank 1 Sensor 2. Took it to Toyota dealer, they confirmed it, and quoted me about $350 to replace the sensor. The sensor alone (Part #89465-60230) was $170.

Thanks for your input, at least I knew what to expect going into the dealer as to what/where the problem was and how much a reasonable estimate was to fix it. Lights went away when the sensor was replaced!

You guys rock!

I know this may be obvious...but is the passenger side downstream right?

I have a Toyota service bulletin T-SB-0398-09 that identifies Bank 1 for the 1GR-FE engine (V-6) as the passenger side and Bank 2 as the drivers side. The Denso downstream oxygen sensor has two part numbers identified as left and right. Left and right sitting in the 4runner or left and right looking from the front?

Left is Driver -- Right is Passenger.

hate to blow the dust off of an old thread... but thanks for the help i am in the driveway now trying to get those nuts off... it's going to be worth it's weight in gold this thread.

I have a V8 with similar issues....from reading Post #22, I'm thinking Bank 1 is drivers side? I got a Bank 1 Sensor 1 code...

I think you are right...
I had to go to the dealer who was able to get the job done.
I bought the part hoping to do the job myself. The first Tech looked at it and then told the advisor- who tried to sell me a new exhaust. Another tech who had some grey hair used it head for something other than wearing his "slightly askew" ball cap. combo of heat and brains got the job done..

I have nothing again the younger techs out there I just wish they were not so fast to give up on something. I do understand that they are on a clock and under pressure to get the job done- so the next car can get in.

Best of luck

It was the drivers side....I got the Denso replacement, with my military discount for about $58. Fortunately, removal and replacement was painless....no more "Check Engine Light"!