More 2000 Sienna O2 Oxygen sensors questions. Qslim ?

There should be ONE upstream and ONE downstream, two total.

Yeah, they work. You may not get the mileage you're accustomed to, or you may not be as clean at inspection as you were before, but they will work.

I use thim in 20 YO Celicas and Tercels when I want them to *JUST* pass emissions. If the van is a beater and you're thinking of sending it to the wrecker's in a year or two, buy the Bosch. It won't HURT (I used one in a '95 Tercel; $30 at the CarQuest I was working at). But if I had the $$$, I'd go OEM.

There is one O2 sensor per bank between the cat and the engine. On a V-6 engine with 2 banks, you would have 2 O2 sensors before the cat.

I have no experience with Bosch universal sensors so I can't comment on how they work, but if you are going to try one, I suggest cutting the pigtail off of the old sensor and splice it to the new sensor so that you don't mess with the harness to the ECU. You then have the option of going back to a factory O2 sensor without any problems.

|> Looked around underneath and found one O2 sensor between the cat and |> the engine, and one after the cat, toward the rear of the van. |>

|> I've spent a lot of time online and with online vendors' help ppl and |> received somewhat contradictory information about what will do the |> job. |>

|> 2 questions: |>

|> 1/ Are there actually TWO O2 sensors between the cat and the engine - |> vendors' sites seem to suggest this - saying "2 required" ? As above, |> I saw only one [towards the passenger side] but wasn't looking for a |> 2nd one at the time. | |There is one O2 sensor per bank between the cat and the engine. On a V-6 |engine with 2 banks, you would have 2 O2 sensors before the cat.

I read that to mean that besides the Air/Fuel sensor [ which is very visable] on the exhaust manifold close to the radiator there is an O2 sensor somewhere on that manifold or whatever it becomes on its way to the cat, that I have not yet discovered - will look when wife returns home with the van. Thanks. Info on Bosch universals below.

| |>

|> 2/ I am a electronics buff and ham-radio operator who would have no |> trouble doing the cut and splice wiring job required to install the |> much less expensive Bosch Universal sensor[s]. Does anyone know if |> they will work with the Calif. emissions engine ? |>

|> TIA, QE in NJ | |I have no experience with Bosch universal sensors so I can't comment |on how they work, but if you are going to try one, I suggest cutting |the pigtail off of the old sensor and splice it to the new sensor so |that you don't mess with the harness to the ECU. You then have the |option of going back to a factory O2 sensor without any problems.

Not having seen one, you guessed it anyway :-) !! That's exactly how they work. Here's a link to the installation guide for Bosch Universals, which sell online for less than $70 delivered.

QE

He also has to obey the color codes and make sure Signal and Ground are wired correctly; the two white wires on the Bosch are the pre-heater and are wired into the heater wires on the connector. I can't remember the codes right now, but i think I googled it, IIRC.

Thanks for the info and anecdotes Hachiroku - not sure exactly what upstream and downstream mean - I think you mean before [upstream] and after [downstream] the cat - if this is wrong further explanation would be welcome.

Cheers, QE =======================

|> Looked around underneath and found one O2 sensor between the cat and |> the engine, and one after the cat, toward the rear of the van. |>

|> I've spent a lot of time online and with online vendors' help ppl and |> received somewhat contradictory information about what will do the |> job. |>

|> 2 questions: |>

|> 1/ Are there actually TWO O2 sensors between the cat and the engine - |> vendors' sites seem to suggest this - saying "2 required" ? As above, |> I saw only one [towards the passenger side] but wasn't looking for a |> 2nd one at the time. | |There should be ONE upstream and ONE downstream, two total. | |>

|> 2/ I am a electronics buff and ham-radio operator who would have no |> trouble doing the cut and splice wiring job required to install the |> much less expensive Bosch Universal sensor[s]. Does anyone know if |> they will work with the Calif. emissions engine ? |>

|> TIA, QE in NJ | |Yeah, they work. You may not get the mileage you're accustomed to, or you |may not be as clean at inspection as you were before, but they will work. | |I use thim in 20 YO Celicas and Tercels when I want them to *JUST* pass |emissions. If the van is a beater and you're thinking of sending it to the |wrecker's in a year or two, buy the Bosch. It won't HURT (I used one in a |'95 Tercel; $30 at the CarQuest I was working at). But if I had the $$$, I'd |go OEM. |

Yup! That's it!

Think of an engine bank as an independent engine - in other words, in a V-6 engine, you would have two 3-cylinder engines that are connected at the bottom. Each of the two engines/banks has two O2 sensors.

O2 sensor #1 is closest to the engine and measures the amount of oxygen in the exhaust and vehicle's electronic control unit (ECU) adjusts how much fuel gets mixed with the air based on what the O2 sensor is telling it.

O2 sensor #2 is after, or downstream of the catalytic converter. It is also measuring the oxygen in the exhaust and is basically there to make sure that the cat is doing its job. If the cat is not cleaning up the exhaust, then O2 sensor #2 would sense it and let the ECU know.

Each cylinder bank has O2 sensor #1 and O2 sensor #2. Besides the O2 #1 sensor visible in the exhaust manifold near the radiator (Bank 2), there is another one in the exhaust manifold near the firewall (bank 1).

As far as i know, there is not a 3rd one in the system, unless that is something new.

Check your local Toyota dealer for the price of an OEM O2 sensor. I may be wrong, but I don't think they are that much more than an aftermarket one.

Good luck!

Last I knew, the Bosch's were running anywhere from $19 to $149, and the OEMs were around $135-175 on the ones I have checked.

I guess it's been a while since I checked on O2 sensor prices!

Actually, even the Bosch Universal sensors are fairly expensive for the Sienna...

For those prices, I'm guessing you can probably buy an OEM Toyota replacement.

Cheers, Nirav

Sorry i didn't get back to you yesterday, Quienes, I was out of town. If you have a Cali emnissions vehicle, then the sensor in your exhaust stream is very different than a regular oxygen sensor. They are called air/fuel ratio sensors, and there are fundemental differences in how they work in their construction the circuit to the ECM in the vehicle. I don't have any experiences with aftermarket AF sensors, but if you go with a Bosch or other brand you should do your research and make sure that they specifically say their unit is compatible with your car. Expect to pay a bit, too. OEM AF sensors are about 240$ (at least at my dealer ship). We always see the rear bank on your sienna go first and more often than the front. I guess it has something to do with the heatbuildup back there while running.

|Sorry i didn't get back to you yesterday, Quienes, I was out of town. If |you have a Cali emnissions vehicle, then the sensor in your exhaust stream |is very different than a regular oxygen sensor. They are called air/fuel |ratio sensors, and there are fundemental differences in how they work in |their construction the circuit to the ECM in the vehicle. I don't have any |experiences with aftermarket AF sensors, but if you go with a Bosch or |other brand you should do your research and make sure that they |specifically say their unit is compatible with your car. | Expect to pay a bit, too. OEM AF sensors are about 240$ (at least at my |dealer ship). We always see the rear bank on your sienna go first and more |often than the front. I guess it has something to do with the heatbuildup |back there while running. ===================== Thanks Qslim for the above information, which has finally solved a lot of confusion. Since the code readout device my tech used said "B1S1 O2 sensor" all my searching around for pricing etc has been for *oxygen* sensors. Having looked at the Toyota box I can see that the one he replaced in the front by mistake was an AF sensor, p/n

89467-41011, as in the one he took out, per numbers around the thimble. So I have an extra, good used one for some day in the future. Next week I think I'll bite the bullet and spring for an OEM AF sensor for the rear bank - because he made a mistake 1st time around, he isn't going to charge me labor for what looks like a bear of a job. Should it turn out to have the same p/n [not likely] we'll just put the new one from the front in the rear and the old one back in the front.

It has been a real pleasure receiving your on-target advice, thank you again and keep up the good work in this ng.

QE in NJ