2005 Silverado came w/2 H2OS sensors only

I have spoken with GM customer service up in Detroit/Pontiac. They tell me the same thing. (must have 4 sensors) I bought the vehicle thru AAA and their car buyers service. AAA was in contact with Mr. Gray who is president of AAA Automark, the repair service for AAA. He stated that they have had this problem also. I, in fact, came into possesion of the vehicle build sheet within the past 48 hours, and found the following. Option “FE9” which is Federal emissions, But, “NT9” is several lines down on the build sheet. “NT9” states emission system federal tier 2 phase out. Now I was told by a different GM mechanic that NT9 means that this truck carries as much load as a 2500HD with the DuraMax diesel/Allison option, so it meets THAT requirement as heavier duty. The dealer that took the truck off the transporter back in 2005 is 60 miles away. So I have been using 2 dealers that are much closer. When I contacted the dealer 60 miles away about this problem, they told me they do not have any record of my vehicle. However, I do have 2 different documents that reflect my truck was delivered there. Sometime today, I will be making copies of all this information and attaching to this blog.

What I want to see you post is something like “Government entity XYZ wants to fine me $10,000/and 6 months in jail because I tampered with my emissions equipment” Until now you are just saying all your grief comes from GM. It appears you are unhappy because your ducks are not in a row and nothing more.

My grief is that my truck is the way it is from the factory. GM/Chevrolet says it is not. I told them then it must be fixed per THEIR warranty which they deny. I have temporarily got the truck inspected, but will go thru this same problem next year, except that it will then be outside of the 5 year/50,000 mile Federal warranty next year. Which means I will have 1 more road block to fight. I just want to prove that Chevy dropped the ball, is responsible, so that I have documentation in the future to show it came from the asembly line like this! Not documentation from an outside source, like the state of NC, since Chevrolet claims that the state is in error, and insinuates that I tampered with the emissions.

Are you finding your 5yr 50K warranty info in your ownwers manual? If not where are you finding it? I am sorry if I am asking for info that is already included in the thread. As it sits know I can find 8yr 80K and 2yr 24K Federal info but no 5yr 50K info, but my text was written in 2005 so that may be the problem.

Federal Emission Control System Warranty, page 16. Light duty truck with heavy duty engine.

Can you provide a link? Is this info in your owners manual? all warrantys that apply to your truck should be in your owners manual. I looked at the schematic for your truck, sure enough there are 4 sensors. Do you only have pre cat sensors or is one side missing sensors

Well I have the hard copy. The part # of the paper manual is: 05CHEVWAR B First Edition. This is in the warranty manual in the same envelope as the owners manual. I have the 2 sensors between the exhaust manifold and the catylitic converters. The 2 ports after the converters are blocked off. I have all the paperwork in 1 place now. I am going to scan it onto disk and attach it to this thread later.

Have you ever checked if you catalytic converters are intact or have been “hollowed out”? As it sits now you have no monitor on your cat. efficiency,you will never get a "check engine " light for any cat. effeciency concerns. If I did not know that defeating the cats. by removing the restriction they impact on the engine is not such a great return I may be tempeted to gut the cats. and remove and plug the sensors.

That doesn’t explain why the PCM is not looking to see a signal from the 02 sensors. Your PCM must have a modified program in some way. I would investigate on how to retrive the version of the program the PCM is using,in paticular I would like to see if GM admits writing a program for a two sensor truck. A Tech2 scan tool could pull the PCM software version, perhaps a advanced generic version scanner could also.

The file is 32,000 KB so I am not sure if it will download or not. Here it goes.

The catylitic converters are not hollowed out. I do not do these things that mess with air quaility. I do have the vehicle build sheet & vehicle component sheet. The part/num broadcast for the ECM is YJHZ. Traceability code is 050817S4M. Does this help at all? I was asking the Chevy dealership about the missing(?) sensors and they “claim” that the diagnostic computer show 4 working sensors.

What I would need to know is the version of the software the PCM is using. This is odd that all your grief comes from the Dealer but the Dealer says that 4 working sensors are shown. How is the PCM dealing with no cat. efficiency input? but the Dealer says there is input from missing sensors. I get the feeling there is a Factory modification going on here that the Dealer you are using doesn’t know about. In short things are as they should be but the problem comes when we can’t understand how.

How would I find the version of software the pcm is using? And I agree there must be a factory modification. But how to find this out?

With a scanner select the PCM and one of the first bits of information will be the version number. I know the GM proprietery scanner (Tech 2) will tell you this but maybe your garage doe not have a Tech 2 scanner, perhaps a advanced version of a generic scanner will spit this info out.

Some how we must find out what version it is supposed to have and compare it with what it does have. This all may be a dead end but something is allowing this truck to work without post-cat. 02 sensors. How could this truck be emissions legal if it is not possible to verify the condition of the cats.? I know we hashed out the issue of a OBD2 car going into closed loop without post-cat 02 sensors a few weeks ago and most thought a out of range reading on a post cat. 02 sensor will not prevent closed loop operation but I am not so convinced. Why does your truck not have a “check engine” light as it would if a post cat 02 sensor was unplugged? I am sticking to the idea of a modified software version until I come up with something different.

I am planning a trip to my old GM Dealer and I will try to present the question but they hesitate to let me in on these type of things, they know I post here. With it being finals week at school I am a little jammed for time but this situation has stimulated my interest.

For the regulars I ask, where is hellokit? his input would be valuable.

Have you reviewed the attachment I placed a couple postings back? It is 32,000 kb but has things like the vehicle build sheet with it and the unknown “NT9” Federal emissions tier 2 phase out.

It’s entirely possible that since this vehicle has a GVWR in excess of 8500 lbs, That it doesn’t have to conform to the same emissions standards of smaller light duty trucks. If’s that’s the case someone should’ve noticed that by now though.

That’s what I’m wondering, but I don’t know enough about this area of emissions & trucks to know. My GVR is is 9200lbs. per tag on door. Per Chevy, it is a light duty truck w/heavy duty engine. The 2005 cataloge states that max. GVCW is 22,000lbs. But the emssions inspector for the state of NC looked in the medium duty book. Would Chevy build a truck for NC but maybe then same truck in New York with different classification, hence 4 O2 sensors? Would that mean I could not register the truck in a different state?

Very possible, different states have different emissions standards. Generally the northern states and California have the most stringent standards. As far as registering it different states, I’m not sure how that works exactly.

I don’t see any performance or mpg or emissions lowering advantage of not having post cat. 02 sensors. What would motivate GM to build a 2 sensor truck and why would a customer want a 2 sensor truck over a 4 sensor truck.

Are the rear sensors left off so the truck can run a richer (or leaner) fuel control program. Or is the whole idea to save on the cost of two sensors?

I want to pursue why (as you have stated) the Dealer says that the presence of 4 sensors is detected by a scan tool.

Can you or anybody here tell me how to get in touch with GM engineering? All document request thru Chevy cust. assistance is refused!

All postees on this thread, I have won my arguement with Chevrolet, after much adue. Per Steve Howell, I have a rare truck with an “NT9” tier 2 phase out emission system. Has something to do with an “NC1” notation. So few of these trucks were built like this, that it was not published in normal circles. Chevy/GM engineering field rep. had to provide an answer. I have demanded that all pertinent documents be provided to me regarding this fiasco, at which time, I will provide to this forum. FoDaddy, your right about the weight rating as it applies to my truck. Thanx for the help here, and as I said, I will be here with more info. in the next couple of days as I get the proper documentation.