96 Tahoe 2 dr.Oxygen Sensors issue

[theghoul]

Hello
Newb here, but been lurking for ages.
I have a 96 hoe 2dr. _ typical 5.7 - pretty much all stock.
SES light's on ...

Had cap, rotor, wires & plugs, Fuel & Air filters tune up a few months ago & while they where in there , they read codes & stated that all 4 02 sensors needed replaced! at $500, no less.

So, Im trying to replace the sensors myself & save some $$$.
State smog is coming up in 60 days...

I ordered 2 sensors last week ( gunna do 2 at a time) of course, when I go to remove old ones, I notice :
A- the uPSTREAM -before cat sensor in the truck has only a single wire attachment ( all parts in the catalogs for '96's have a 4 wire connection,which is what they sent me, '95's have 1 wire?)

B- the 4 wire connector on the real sensor is a diff. configuration as well!

So obviously i need t exchange the parts.
BUt...Should I order a 95 1 wire sensor for both the pre-cats?
Will the computer read those ok? or keep throwing codes?

BTW-as trouble shooting this SES light issue, i've cleaned TB, & removed & Cleaned EGR & plan to do the IAC too.

Im sure some of you have had this situation before...
Any help ?
Thanx!

 

[oldsalt]

So after the the tune up and the scan did they clear the codes so the SES light goes off. If so, are you still getting the light? If not, I would just leave the O2 sensors alone. You can go to get a smog check and if you don't pass they will recheck for free after you do your work.
I checked the rock auto catalog and they only show 4 wire-all brands.

 

[theghoul]

Thanks
Yes, the light WAS out for a few days...then back ( comes on when on freeways, going up an incline )
its been on constantly for a month or so.
I did disconnect battery for 1/2 hour & the SES went off...for a few more days, but back now.
As for the 1 wire 02's...
Im wondering if they overlapped years for parts? maybe early 96 still had 95 parts ?

Dunno.
ALso, I've been getting ( after warm up ) real rough idle at stops...only when in gear ( when in Ntrl & park its fine )
from what I read, I thought the EGR & TB cleaning would fix or help that, but it's still there.
I doubt the 02's would effect idle?

 

[oldsalt]

Let's start off with the cheapest possibilities/fixes

Freeways and incline-- Try replacing the fuel filter (it's on the inside of the frame under the drivers door) My sister has a '99 2door that was having the same problem and a new fuel filter fixed it right up.

rough idle-- Replace the Idle Air Control valve.

02's-- Sure enough. I just looked at the Rock Auto catalog for '95 and they have both 1 and 4 wire listed. You can try this, get your VIN number and call or go by a dealer and ask them to tell you what O2 sensors that you have. Don't know what part of SoCal you are located, but the Chevy dealer in Cerritos had some pretty accommodating guys in the parts dept. I forgot what the name use to be but it is now a Penske dealership.

Also if you can see if Autozone or some other place can do a scan for you, find out the code numbers. That would help point you in the right direction.

 

[retorq]

Not all 95s have a single wire. I could have sworn mine did so I get a generic 3 wire that I Was going to wire up and when I got under there, there was already a factory 3 wire. Autozone showed a single wire and a 3 wire.

Single wire and a 3 wire can be interchanged, the 3 wire has a heater thus heats up and ready to go quicker. The voltage read out should be the same for all narrow band O2 sensors .. GM style anyways.

 

[SunlitComet]

With the exception of some freak of nature OBD2 systems require a 4 wire oxygen sensor front and back if you only have a single wire I would suggest some on has modified your system and you are probably getting code related to the O2 heater and sensor circuits or fuel mixture. there may be a slight difference in front to back plug config.

 

[theghoul]

With the exception of some freak of nature OBD2 systems require a 4 wire oxygen sensor front and back if you only have a single wire I would suggest some on has modified your system and you are probably getting code related to the O2 heater and sensor circuits or fuel mixture. there may be a slight difference in front to back plug config.

Thats what i was wondering...But the connections on mine (at the harnesses )look stock, or at least not Spliced or hacked...so I didnt know if some '96's came w/both 1 & 4 wires or if mine was some anomaly.

And , of cousrse , in California you CANT get codes read @autozone etc. for free anymore...new law.
nice of them, isnt it?

 

[SunlitComet]

Law? I was told local shops were complaining about losing business to the parts stores. I don't suppose you have a link to that law do you? I don't trust shops that much so I have my own scanning equipment. I get to keep the data and take my time going over it.

 

[theghoul]

yea, Thats what I was told too...Just here in cal.
Don't know if its a legit law or just an excuse not to give us info for free!
All other Autozone except in Ca. are supposed to scan for free.

In any case I still have some codes popping up & SES light on constantly.
I kind of only 1/2 trust the mechanic & the parts store...

 

[retorq]

You can get a cable and free software to load on a laptop and read them for free ...