Oxygen sensors

Rockrz · Post by **Rockrz** » Sun Mar 23, 2008 8:06 am

How many O2 sensors do you have?

My '96 4.3L has 4.
Just curious if the newer trucks have fewer O2 sensors.

Post by **HenryJ** » Sun Mar 23, 2008 8:11 am

Where are they positioned. My neighbors '96 has three just like my 2001. One for each bank and one post cat.

Rockrz · Post by **Rockrz** » Sun Mar 23, 2008 8:27 am

Mine has 2 that are close to the exhaust manifolds on each side, and two more further out, closer to the Y in the exhaust pipe.

I had to change these all out after having a local exhaust shop weld on a new Cat (the old one clogged)

After the new cat, I kept getting check engine lights and the code was for O2 sensors.

Since I was going to be planning on driving the truck long term, I replaced all O2 sensors and check engine light has never come on again since.

From now on, I'm going to remove the sensors before doing any welding since it appears that the excessive heat may have damaged at least one of them.

When you say "post cat", is that after the cat?
Mine doesn't have one after the cat, and the cat doesn't have a air line going into it either.

Post by **HenryJ** » Sun Mar 23, 2008 9:01 am

No airline here either. Yes we have a post cat sensor. It measures converter efficiency.

My Old '86 has only one O2 sensor.

Torskdoc · Post by **Torskdoc** » Sun Mar 23, 2008 9:08 am

Do you have CALIF. Emissions???

My 2002 has 3. One each on either side of the "Y" pipe(pre cat) just off the exh manifolds, and one (POST CAT) btwn the cat and muffler. My dad's '95 jimmy is the same. All of the S-10 4.3's I've seen from underneath (to many to count) have all had 3. Live in Md with Fed Emissions.

One other explanation, is that your exhaust system has been modified from original at one time by a prior owner.

Not all cat's have what I call an boost air line. They have gotten more efficient over the years and very few if any come from the factory anymore with the line.

Most auto stores are incorrect in that they list the S-10 with 4 sensors. 2 pre and 2 post. The theory is that there should be a minimum of 2 (1pre and 1 post) up to a max of 4 (1pre and 1 post pre bank on a true dual set). The way our factory exhaust is set up you are factory equipped with 3. One precat sensor for each bank and a postcat sensor. All the postcat sensor does is check the mixture coming out of the cat to make sure it's actually working as it's supposed to.

Larry

Rockrz · Post by **Rockrz** » Sun Mar 23, 2008 9:20 am

Torskdoc wrote:Do you have CALIF. Emissions???

I dunno.

I do know that the stock pipes appear to be stock and there doesn't appear to be any wiring for a post cat sensor, unless someone went the trouble to remove that wiring.

I bought the truck second hand here in Texas, but I guess it could be California emissions.

I guess that would be good, since California people obviously love mother earth more than the rest of us

roadrunner · Post by **roadrunner** » Sun Mar 23, 2008 10:43 am

You used to be able to tell if Calif emissions or not on under hood engine tag. Not sure now. Mine says conforms to some federal regulation number AND Calif emissions. Maybe they've been combined nowadays?

BTW, mine has 3 sensors. One each down section of Y pipe and 1 after the pre cat and main cat but ahead of the muffler.

24digger · Post by **24digger** » Sun Mar 23, 2008 3:26 pm

I'm almost positive my 95 Z has just 2 one right before cat and one after.

I thought my crew had 3 one on each side of y-pipe and one after cat.

I'll have to go check you got me wondering now

quickbiker · Post by **quickbiker** » Sun Mar 23, 2008 6:32 pm

I got 3 total. Never replaced mine, but maybe I should, dunno. 106k miles now.

roadrunner · Post by **roadrunner** » Sun Mar 23, 2008 7:37 pm

Replaced my right bank sensor once thus-far. Due to mud tearing off wires at sensor. Hence why I went after and bought skid plates.

Rockrz · Post by **Rockrz** » Mon Mar 24, 2008 5:16 am

quickbiker wrote:I got 3 total. Never replaced mine, but maybe I should, dunno. 106k miles now.

I bought my truck with 107,000 miles on it and I didn't change mine out till about 120,000 when I had my cat replaced and one of them went bad.

Post by **HenryJ** » Mon Mar 24, 2008 7:26 am

Changed mine this week. 73,335 miles on them. One had set a code three separate times for a heater failure. It has been my experience that they fail in a cascade. That and the fact that they degrade over time , was the push to replace them. Hopefully I will regain a little performance and mileage.

The Stock sensors were the bulb shaped AC sensors with the slots. I installed AC Delco which are more of a cylinder with holes. I have no idea what difference the design makes. The AC look extremely close to the same as the Bosch sensors. Some have had problems with those. I have not. Still I opted to go with AC Delco.

quickbiker · Post by **quickbiker** » Mon Mar 24, 2008 3:14 pm

You just gotta soak it in mud holes more often, but then the air pump goes more often, dunno which is easier to replace.

24digger · Post by **24digger** » Mon Mar 24, 2008 3:20 pm

Yep my 95 has 2

my crew has 3

Henyj where did you pick up you 02 sensors?

how expensive were they?

Post by **HenryJ** » Mon Mar 24, 2008 3:23 pm

I bought them from Rockauto.com and used Reeds discount code. Fifty sumth'n each.

purduecrew · Post by **purduecrew** » Mon Mar 24, 2008 6:41 pm

thanks guys, i must have jinxed myself with yalls help. set the code for the other 02 sensor today. bank 1. drivers side correct? I replaced the passenger side one at 85K, and this one is at 107K. I think its time.

roadrunner · Post by **roadrunner** » Mon Mar 24, 2008 8:12 pm

Might as well make it a clean sweep an get #3 also!

quickbiker · Post by **quickbiker** » Tue Aug 12, 2008 5:30 am

I hit the P0137, bank 1 sensor 2 code over the weekend, it hits about 2-3 times a year now.

What part #'s and what brand are you all getting? I'm thinking AC Delco, but they are a bit steep. I'm not sure about the universal ones, ugh. And were you all getting them? And I guess at miniumum, I should replace the 2 pre-cat sensors.

Post by **HenryJ** » Tue Aug 12, 2008 6:10 am

I bought all three through Rockauto.com. Check the classifieds for as discount code. I prefer to stay with the AC Delco oxygen sensors that are tailored for the OEM application.

I have had some problems with Bosch sensors and have no need to assemble or splice wires using a universal sensor.

roadrunner · Post by **roadrunner** » Tue Aug 12, 2008 3:43 pm

quickbiker wrote:I hit the P0137, bank 1 sensor 2 code over the weekend, it hits about 2-3 times a year now.
What part #'s and what brand are you all getting? I'm thinking AC Delco, but they are a bit steep. I'm not sure about the universal ones, ugh. And were you all getting them? And I guess at miniumum, I should replace the 2 pre-cat sensors.

Bought all three of mine on E-bay. Seller store: Global Automotive $19.99 each plus $12.00 shipping. One was defective on arrival and they replaced it free of charge I just had to pay shipping to return the defective one. All three working 6 plus months now no problems. BTW they were direct fit for my 01 4.3W no adapting needed.

I'd replace all three at once if I were you. Usually the third one isn't far behind if one or more others fail. JMOP.

Rockrz · Post by **Rockrz** » Tue Aug 12, 2008 7:07 pm

24digger wrote:I'm almost positive my 95 Z has just 2 one right before cat and one after.

Yeah, I was changing my oil recently and while under the truck I thought I'd look instead of going by memory...

And, yep. I've got three, just like you do.

I replaced mine with Bosch and that was a long time ago and they've never given me any problems. They were direct replacement where they plugged right in.

quickbiker · Post by **quickbiker** » Sun Aug 17, 2008 3:45 pm

Yea, Rockauto had 2 different Bosch's listed, one is universal and other is direct plug-in, oem. I just put the Bosch's in last week and no codes so far. I skipped the one after the cat since it seems like a useless one. I wonder if that one would even set a code off?

Rockrz · Post by **Rockrz** » Sun Aug 17, 2008 4:53 pm

You know, I changed my oil for the first time over the weekend on my new '03 truck and it's doesn't appear to have an O2 sensor after the cat like my '96 does.

roadrunner · Post by **roadrunner** » Sun Aug 17, 2008 7:42 pm

quickbiker wrote: I skipped the one after the cat since it seems like a useless one. I wonder if that one would even set a code off?

Yes it will. P0136 thru P0141 all apply to that particular sensor representing different failure modes for it.

quickbiker · Post by **quickbiker** » Tue Aug 26, 2008 2:27 am

I don't remember one being listed for the rear. Is it the same one that goes before the cat?

roadrunner · Post by **roadrunner** » Tue Aug 26, 2008 11:41 am

Yup! All three the same on the 01's.

LUVMY02CREW · Post by **LUVMY02CREW** » Sun Feb 08, 2009 5:04 pm

I've been resetting/clearing code P0135 with my Scangauge almost everyday now for quite some time. So.....I'm finally gonna break down and be ordering 3 of these o2sensors from the same ebay seller that roadrunner got his from....Global-Automotive.

They are DELPHI brand so they should be aok right....didn't see any mention of 2wd vs 4wd about them.

I checked at rockauto.com and even with discount code from classifieds here, they were gonna be nearly 2x cost

I guess one year difference in truck age can make a great diff in cost

roadrunner · Post by **roadrunner** » Sun Feb 08, 2009 5:19 pm

Ad looks right. Still running mine with no problems.

F9K9 · Post by **F9K9** » Sun Feb 08, 2009 5:27 pm

Mine's an '03 w/three sensors. There are two things that I will not buy that are not ACDelcos. O2 sensors and fuel pump assemblies. I hope you have had good luck with Bosch or whatever but, with my luck, I'll pay the extra bucks.
I just replaced the bank 2 sensor yesterday with an ADelco one. It was $80 and change from RockAuto but, I know it is good. I also realize that the others will cascade into failure shortly so, I went ahead and cleaned them and reinstalled with anti seize. They'll be a 5 min swap when the time comes.

killian96ss · Post by **killian96ss** » Sun Feb 08, 2009 6:17 pm

I've tried other brands of 02 sensors like Bosch, NGK, etc, in some other GM vehicles and experienced slight surging problems and lower gas mileage so I stick with AC Delco 02's in all my GM vehicles now.

I'm not saying that all the other brands of 02's out there are no good, but it seems to be a gamble when you stray from OEM components.

Delphi supplies the majority of GM's electrical components so I'm sure their 02's are probably ok.

Steve