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Help please! 2005 Chevy Avalanche 1500 oxygen sensors!

BigPapiCares

New Member
Joined
Oct 20, 2016
Messages
7
Hey there everybody! Need some help regarding O2 sensors on my 2005 Chevy Avalanche 1500 LT. What I'd like to get some straight forward answers to are this: 1) Are the upstream and downstream sensors the same exact part or different? I know theres 4, I know one of them is bad, I need to change it out, I have found many informative videos, pictures, diagrams, I've found parts numbers that match for replacements, I just want to know before ordering the sensor if its for sure the right one, I've have it diagnosed(like 3years ago lol) and of course forgotten which one it was, but thats something I'm still working on to finding the papers from that diagnostic. 2) Is there a SPECIFIC brand that I should be buying as replacement? I see denso, bosch, acdelco, all that say fit with my vehicle, I just want to be sure. Thanks in advanced for any input!
 
First of all welcome to the site!

I've replaced one on my '03 and I used the Bosch version which I picked up from a local auto parts store.  The code (Pxxxx) you get when the check engine light is on will pinpoint exactly which one(s) need replacement.  I can offer you the following advice:

1) Don't change ones that don't need replacement.  Reason why?  Well there is a good chance that when you back one out, it will strip the threads.  It has happened to many of us on this site.  The problem is the exhaust pipe and the threads get fused over time because of the type of metal and all the heat that goes to that area.  If you strip the threads, you will be going to a muffler shop to have a new bung (with new threads) welded to accept the new sensor.  You can drive without the sensor in place, but your avalanche will sound like a tank, and I don't advise going any further than needed to get to the shop.  I was able to get someone to weld a new bung on mine for 50 bucks.  Don't assume that you are better than us because you know how to use a heat torch and PB blaster on the threads first...  we did that as well and it still stripped on the way out...  LOL

2) Don't buy one of those O2 sensor sockets with the wire cutout to remove your sensor.  Why?  Well, usually it takes a LOT of torque to back one of the sensors off.  Those specialty sockets will flex and round out the hex head of the O2 sensor.  Instead, you should buy a 6 point deep socket of the correct size and just cut the wire.

 
Auto Zone and Advance Auto will check your codes for free.
Those two are under a mile from me, others will do it free too.

I'm completely sure I toasted my transmission due to an O2 sensor along with MAF faults I ignored. Trust me, it's cheaper to fix those faults than have your transmission rebuilt. 

 
Upstream are different from downstream.
 
I would get the codes read again also and post the code, but if you really drove it like that for 3 years you may have caused yourself more problems.
 
marzahld said:
2) Don't buy one of those O2 sensor sockets with the wire cutout to remove your sensor.  Why?   Well, usually it takes a LOT of torque to back one of the sensors off.  Those specialty sockets will flex and round out the hex head of the O2 sensor.   Instead, you should buy a 6 point deep socket of the correct size and just cut the wire.
x2  In addition, the O2 socket tool is a 7/8" socket whereas the )2 sensor is actually a 22mm.  I ended up rounding mine off using the stupid tool.
 
There are just somethings I will only purchase OME like sensors.
A lot of members on here have had problems with aftermarket 02's.
Before trying to remove use BP-Blaster or like penetrating oil not WD-40.  
Some members have soaked them for days.
 
My experience may be different than yours...

And my views may conflict with others...

With those warnings...

Downstream o2 sensors are for testing the Cats only. Don't believe brand maters and can be bypassed with "emulators" (Note" emulators are illegal for on street usage and intended for use by race vehicles without cats that still maintain factory PCM)

Upstream sensors should be looked at similar to spark plugs. They do loose efficiency over time as they get coated with carbon emissions from normal exhaust. It is smart to replace these sensors like you would spark plugs but depends on your preferences. If you replace one, replace the other at the same time. They can be had reasonably priced off sites like Rock Auto. Due to different brands having slightly different response curves and due to the PCM being picky most of the time I can only suggest using AC Delco for these.

I also suggest using a shop to install the sensors. They CAN be easy to remove but can also strip the threads if you don't do it right. This is one of those things that if your local muffler shop will replace them for $25 labor why bother doing yourself.

Not having these replaced when you got the initial code means you likely have been burning up gas way faster than you should. The biggest issue that can cause is plugged cats that I am aware of other than a lighter wallet than should be.

And most parts places will check your codes for free.
 
Wow what great responses! I appreciate it! I will get the codes in the morning. I think I'll just have Midas put it in when I have them do the tie rods, might as well, wish I wouldnt have waited until now to do this with the cold and crappy weather. I haven't noticed any transmission issues at all but I totally understand this O2 sensor is now pretty imperative to get changed out. Up until the last 2months, if I really punched it like getting on the freeway, the check engine light pops on, but then goes off on its own within a few hours. But here in the last 2months its happening more and more frequently, and yeah the check engine light turns off within hours to a couple days but yeah, still something thats gotts be done. Will post codes asap. Thank you all again for your responses!
 
BigPapiCares,

I'm no expert but I had my transmission rebuilt at only about 50,000 miles by a reputable shop. I'm certain they weren't trying to gouge me when replacing the MAF and O2 sensors. I'm less than certain if they caused my transmission failure. As others here posted the MPG alone is a good enough reason to replace them. There are instructions on here about cleaning your MAF.
It seems to me they go hand in hand, if your MAF is dirty you're using more fuel so it makes sense you'd foul your O2 sensors sooner so it would work the other way around too. Good luck.
 
P0174 = Fuel Trim System Lean (Bank 2)
P0171 = FUEL METERING TOO LEAN
P0101= MAF Sensor Signal Range/Performance

I suggest punching those codes into a GOOGLE search and see what comes up.
https://www.obd-codes.com/forums/viewtopic.php?t=11524

 
If you have more than 100k on the front O2's then they should be changed..

But you have a P0101 code, MAF Sensor Signal Range/Performance. A bad MAF will cause the other 2 codes you have, so my recommendation is to fix that one first and the P0171 and P0174 will probably go away..
 
Before you dive in too much deeper...

The symptoms you describe and the codes you throw are indications of an intake leak. The early models of 5.3 had a poorly engineered intake gasket.

First signs of this intake leak are the lean codes you mentioned. You will also see that you may throw codes when the engine is cold but they clear once the engine is warm and the gasket seals up. This problem will get worse the colder it gets...

When I changed the gasket in my truck it was only throwing the code when it was below 20F.

But this can cause irregular shifts and lots of other issues.

The fix is to replace the factory intake gasket with a newer model. STRONGLY suggest felpro because they are way better than the re-engineered factory ones. The dealer instructions state that the intake bolts are stretch bolts as well as the washers and need to be replaced when doing the intake gasket.

Also a common failure is the rear Knock sensor. I mention this because you have to remove the intake to get to the knock sensor. You can view the many threads on the intake gasket leaks as well as knock sensors. Just a good idea to replace the knock sensor too along with the wire harness if your already into the intake...

Other than cleaning the MAF and checking into replacing the front o2 sensors I suspect you change your intake gasket and you will find your truck drives almost like a new truck again.


If there is any way you can do this job yourself you will find it costs in the neighborhood of $150 to do yourself. If you pay a shop to do the intake gasket make sure you request the felpro only gasket and to replace the rear knock sensor and harness, show them the TSB that is shown in the knock sensor threads. I was quoted $300 to do just the intake labor by a local shop but it is not hard to do and takes an afternoon. 
 
Interesting. Okay so, I'm thinking maybe I should just go get it re-diagnosed seeings how this was like 3years ago. But can anyone tell me the brand and part #s to for the 2 upstream and 2 downstream oxygen sensors, since they are different?
 
Looks like Part# 19209808  OXYGEN SENSOR for both left and right on GM Parts Direct
It doesn't specify front or rear, I'm sure someone will correct me if I'm wrong, I'll look further.

redheadedrod said:
... may throw codes when the engine is cold but they clear once the engine is warm and the gasket seals up

But this can cause irregular shifts and lots of other issues.

With my short commute to work and cold climate that may be how I toasted my transmission. Too late now as some kid totaled it running a red light several weeks back but I'd be looking at changing that intake gasket if I still had the truck.
 
Rock auto is your friend
 
I've pretty much searched and searched for the answer to what the part numbers are for the upstream and downstream sensors. Maybe my local chevy dealer could help? And by the way, in the 4 years I've had my Avalanche, any questions I ever have and google search almost always brought me to this page with answers. Love this site!
 
>Rock auto is your friend

x2...  If you're not aware, Rock Auto is a website where you can search by vehicle for parts and it works well.  Usually really good pricing too.
 
http://www.rockauto.com/en/catalog/chevrolet,2005,avalanche+1500,5.3l+v8,1430977,emission,oxygen+(o2)+sensor,5132
 
Rock Auto is good for parts, shopped there many times. The only issue I have with them is if your orderings multiple parts they may ship from many locations and they charge you shipping from every warehouse.

I was ordering about $250 worth of parts one time and the shipping was going to be $60.00 plus, so I did not complete the order and went to Summit Racing with the part numbers and most of the same parts there with free shipping when your spend over $100 no matter how many warehouse they come from.

Just my experience..
 
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