OK...learned this much.

Sensor 1 means that this is an upstream sensor, which I'm guessing will be in fairly close proximity to the exhaust manifolds.

Bank 1 (as opposed to Bank 2) means that this is the sensor that handles Cylinder 1, 3, & 5. Can someone please confirm that 1/3/5 cylinders are the firewall side of the engine or the radiator side?

So, the difficulty on getting to this? Do you get to this sensor from the engine bay or from underneath? I was just about to change the spark plugs which will entail pulling out the plenum (or so I have been lead to believe). If the sensor is in the same location, I could get both done at the same time.

Suggestions on sensor brand/model or is it preferred to use a Toyota OEM part?

 

Got the information from tech. 135 are closest to the firewall, and 246 are on the radiator side.

 

Have the same issue. Got a P0031 code. Did you end up doing this repair yourself? Was it difficult. If you had it done at a shop, what did it run you?

Thanks

 

same code p0031. when i tried to get sensors from a carquest, their computor only read that 2008 le sienna had 2 o2 sensors. one for radiator below cat and firewall below cat. i can see the sensor for above cat at radiator. so what gives? how many o2 sensors are there? i can assume there are 1 before and after cat on bank 1 and 2?

 

There definitely four on the 2008 Sienna. Two pre-cat and two post-cat front and rear.

 

yeah thanks. pre-cat i assume are a/f sensors and post-cat are o2 sensors. pricey lil bastards

 

Yes they are. I got prices ranging from $170 to $270. I was told by many not to use the universals...only the direct replacement. Toyota wanted $219 for the part and $360 to do the whole job so...considering it is on the back of the engine and I an being told it is the most difficult one to change, I am going to let Toyota do this one.

 

I have used universal ones before and they seem to work fine. Just make sure the universal you get are with in range/specs for your car. Although they are universal but only to some extent.
If you go to an auto parts they will still ask you for year, make and model of your car even though you want universal o2 sensors.

 

k heres the deal. there are two air fuel sensors. the air fuel sensors are located before cat convert. one is in front. easy. $175 for sensor. the second a/f sensor is in back near fire wall. a real bitch. $175 for sensor. you can get to it from under van to get it unplugeed but after 20 minutes of swearing, i found it eassier to get it loose from above with lots of extensions and another buddy underneath the vehicle lining me up. i had swivels and ratchets galore and could not get it off from underneath. O2 sensors. Two after cat convert, one on each side. by radiator and firewall. easy and can be done from underneath. one sensor was $85 and the other was $120. all in all the four sensors cost me $550. Toyota wanted alot more. all my codes and check engine lights are gone . a buddy had the code scanner to to clear my codes out and everything reads out fine. my problem was upstream. the two a/f sensors were out which is what probably took out my spark plugs. thats all i got. hope this helps somebody.

 

WOW! You replaced all of them? I had Toyota change just the rear per-cat and my codes are gone. $360 and done....no swearing at all.

 

I was told to remove the wipers and the cover under them and S1B1 will be right there. I haven't done it because too many bolts to remove plus the all the wiper motor and rods assembly has to also be removed.

$360 is a good deal; Dealers in Los Angeles county want $480. I bought the sensor $170+tax (wholesale price new year gist deal).
I am hoping to find a mechanic that will replace it for up to $150 labor
my code was 2195 stuck on lean.

Thanks for the info, it was helpful.

 

You can buy the OEM Denso sensors from rockauto.com for $95. The tool can be rented for free at autozone or bought for $10. I cant believe the dealer charges so much. Dang! They make $100 on the sensor and another $200 to turn a wrench and plug in a wire connector per sensor. What a scam. Oh but you get free coffee. That makes all the difference in the world.

 

Be cautious about changing the sensors without determining what is causing them to read lean. Try to get a better diagnoses.

 

I went to AutoZone to get the check engine (VSC / Trac off) light diagnosed (for free!). The bank 1 sensor 1 O2 sensor pumping circuit was lower than the minimum acceptable value and needs replacing.


Just got a quote from the dealership for $515 to replace to replace the O2 sensor bank 1 sensor 1. The part from the dealership cost $269.59.

 

2005 Sienna with 130,000 miles

On way back from 300 mile road trip, CEL light popped on last night. Took it to Autozone this morning to pull the codes. It was a few key cycles before we could get the OBDII reader to communicate with the vehicle. By then, the CEL had gone out. So, we put it on a live reader, and could see that the voltage of Bank 1 Sensor 1 O2 sensor was really high...like 3.5V. The other two sensors were still hanging around under 1 volt. So, with not entirely complete information, I'm betting the Bank 1 Sensor 1 O2 sensor needs to be replaced.

Could someone tell me the location of Bank 1 Sensor 1, how difficult is it to get to, and recommend a decent O2 sensor brand/model to replace it?

Thanks in advance.

 

 

Be absolutely certain that sensor isnt an AFR sensor!! They run at a bias voltage of 3.3V so a reading just fractionally high could be fine