Quick question: sub-heated oxygen sensor
 

Howdy

I live in good ol California so my truck uses a sub-heated oxygen sensor. I'm trying to find one on the internet but can't find anything that says sub-heated. I've seen before and after the catalytic converter and heated and non-heated. Are any of those another term for sub-heated?

Sub-heated? Can't say I've heard of a sub-heated O2 sensor. How did you determine?

Oh, yeah...what are working on?

3VZE. The service manual calls it a sub-heated oxygen sensor.

What year?

Sub-heated is the one after (downstream of) the catalytic converter CALI only. See diagram:

http://www.ncttora.com/fsm/1990-1995...e/descript.pdf

I learned something new....never heard the O2 sensor called a sub-heated sensor before now. :)

RockAuto has them. Look for the ones called "downstream."

How did you determine you needed one? If the heater fails it will throw a code, but other than that there isn't much (detectable) that goes wrong with them.

Just so you (well, the others) know, the purpose of the sub heated sensor is to monitor the cat. If the second sensor tracks the first sensor as it switches back and forth, then you know the cat isn't doing anything and needs to be replaced.

I crawled under my truck and my oxygen sensor is before the catalytic converter. Does anyone know if sub-heated o2 sensor were require on later models? Mine is a 1990.

Now you've got us all confused.

Only California trucks have the second O2 sensor, right after of the Catalytic Converter. If you don't have the second O2 sensor, a) yours isn't a CA truck, b) your second sensor was kidnapped, c) there was a CA truck made w/o the sensor.

Mine (1994) has it, I can't say for sure when they started, but I'm pretty sure a 1990 truck would have it. But why do you care? If yours isn't really a CA truck (how do you know where it's been these last 22 years?), we're still glad to have you here.

I'm really confused too! The sticker under my hood says it meets all emissions regulations for the state of California for the year 1990 or something to that tune. It definitely doesn't have a second o2 sensor. So I guess they weren't required that year...

Do me a quick favor. In the center of your diagnostic connector should be a slightly (7mm) raised column of two sockets, labelled Ox1 and Ox2. If the plastic frame is there but the Ox2 slot has no metal in it, then I think they were producing 1990s with the second O2 sensor, but you don't have it. (Maybe someone replaced the hood at some point...) If you have an Ox1 connection but no place on the connector for Ox2, then maybe 1990 was too early.

Don't worry about it; the second O2 sensor is not going to make much difference in your life either way.

I went to http://www.sparkplugs.com/results_app.asp, and didnt get a California model until '94. All of the upstream O2s used the same part number (denso),I had a 91 truck I was a California Emissions truck so ther site may not have all info needed, but they have always worked great for me, no complaints. It will say on the label under the hood if it is a Cali truck.

Edit.. My truck was a 22re and one way I can spot a Cali truck is it will have a wire/sensor on the EGR, dont know if the 3.0 is similar. "Cali EMiss" on the a white label with blue writing (if I recall right) and O2 behind the cat converter on the older models.