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2007 Toyota Sienna P2195 O2 Sensor - replacement advice needed

Hi, I have a p2195 trouble code with my 2007 Toyota Sienna CE. This is O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1.

I am assuming I’ll need to replace this sensor.

It’s a little confusing but if I am reading my Haynes manual correctly, the repair goes as follows:

  • The sensor for 2007 and later models will be in the exhaust pipe after the catalytic converter.
  • To remove it, it’s necessary to remove the passenger seat, disconnect and snake the pigtail through the grommet in the car floor. Then, disconnect the O2 sensor from underneath the van and replace.

Has anyone on this forum done this repair on a 2007 Sienna? If so does the above description sound accurate for how to fix it? Do you have any suggestions/advice for someone attempting the repair for the first time? Also, any advice for where to buy the replacement O2 sensor?

I really am not familiar with your vehicle but most vehicles of your year model have 2 - 02 sensors per bank . There is usually a bank 1 sensor 1 & a bank 1 sensor 2 . Sensor 1 is pre cat & sensor 2 is after cat .

I just checked RockAuto & they list both upstream & downstream 02 sensors for an 07 Sienna . Upstream is sensor 1 - pre cat & downstream is sensor 2 - after cat .

Here is some good info

Thanks for the information. Here’s the section of the Haynes manual with a pic of Bank 1 sensor 1.
Can anyone tell where the sensor is located?

Bank 1 sensor 1 is mounted on the exhaust manifold at the firewall.

And if this sensor requires replacement, the exhaust manifold has to be removed because they didn’t provide enough room between the manifold and firewall to replace that sensor.

Now isn’t that special?

Here’s the converter/manifold showing the bung for the air/fuel ratio sensor.


Thanks Tester. I am still confused though because the manual says (see top/center of that pic I posted in Italics): “On 2007 and later models, the air/fuel sensors are mounted at the exhaust manifolds and the oxygen sensors are mounted downstream in the exhaust pipes”.

Is the bank 1 sensor 1 on the 2007 model actually an air/fuel sensor then? If so why does the code say “O2 sensor” ? Is it just a generic code but it could really be an air/fuel sensor? Questions, questions…

It’s simple.

You’re following a Haynes manual’s instructions.

If you want detailed instructions for maintenance/diagnostics/repair for your vehicle, subscribe to an on-line repair service.

This has to be one of the best for the price.


Tester - thanks for the tip.

Toyota uses air/fuel sensors for the upstream sensors. Oxygen sensor is a general term, not completely accurate in this case. Bank 1, sensor 1 is an air/fuel sensor on that vehicle.

Thanks Nevada_545 - that clears it up. I’ve found the part on amazon. From looking online it looks like the sensor is a p.i.t.a. to get to but might be do-able from beneath the van without removing the exhaust manifold.

So, more confusion… :slight_smile: I was checking sensors on rockauto and came to a page of o2 sensors that has confusing terminology. I know the sensor that I need is “upstream” but there is “right” “left” “front” and “rear” for these sensors. See:,2007,sienna,3.5l+v6,1434683,emission,oxygen+(o2)+sensor,5132

How do I tell which of these sensors will fit?

I might have answered my own question - it looks like based on this page that I need an upstream right or rear sensor. The denso part number is 234-9012. Does this sound right?

A - 4 cylinder engine only has 1 bank & a V6 or V8 has 2 . On an engine that has 2 banks , bank 1 would be the bank that has # 1 cylinder in it . Sensor 1 in either application is upstream & sensor 2 is downstream . Bank 1 on your vehicle is the side toward the firewall .

Looking at RockAuto’s website , it can get a little confusing since some brands list front & rear & other brands list left & right .
I have to assume in your application you need either an upstream right or rear , right or rear depends on the brand but should be the same sensor .

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