can I flash PCM to remove CARB emission programming?

[Nate07Tahoe]

Hi All,

I have a 2007 tahoe 5.3 and it had a cat effeciency light on when I bought it. I purchased a new CAT Y pipe with both cats, and installed 4 new oxygen sensors. I am still getting the code, so after some research I have found my tahoe is built to California CARB emission standards...so if I understand correctly, the regular federal EPA cats don't meet my computers CARB level emissions.

1) Can I flash my PCM to remove the CARB standards so that I won't have a code?

2) Can I replace my PCM with another tahoe PCM that is non CARB?

Please help...truck runs terrific but this engine light is very depressing after doing manifolds & cats etc.

 

[Doubeleive]

short answer is maybe if you can find a tune and use HP tuners, otherwise trying to do it with a tech2 or something is probably not possible because it goes by the vehicle vin number.
I am also somewhat curious about why the code is still happening from what I have gathered and I could be wrong is that there is not that much difference in the cat's
you could possibly have the issue resolved with a basic tune from blackbear @BlackBearPerf ? I'm just speculating.

 

[Geotrash]

Hi All,

I have a 2007 tahoe 5.3 and it had a cat effeciency light on when I bought it. I purchased a new CAT Y pipe with both cats, and installed 4 new oxygen sensors. I am still getting the code, so after some research I have found my tahoe is built to California CARB emission standards...so if I understand correctly, the regular federal EPA cats don't meet my computers CARB level emissions.

1) Can I flash my PCM to remove the CARB standards so that I won't have a code?

2) Can I replace my PCM with another tahoe PCM that is non CARB?

Please help...truck runs terrific but this engine light is very depressing after doing manifolds & cats etc.

I think this is a red herring. Are you sure you fixed whatever killed the first set of cats?

I have a 2008 Land Rover that was purchased new in California and installed a new cat on one of the exhaust banks after a bad ignition coil took it out. I installed a non-CARB compliant cat because at the time that was still legal in Colorado. No adverse effects whatsoever, and it passed every emissions test with flying colors. Like Wes, I have read that the difference between the carb and non-carb is the certification process. Some sources say that carb cats have more precious metal loading but others say that they don't and that the primary difference is the certification and ID number stamped on the cat.

I would have Blackbear tune it and call it a day.

 

[swathdiver]

Hi All,

I have a 2007 tahoe 5.3 and it had a cat effeciency light on when I bought it. I purchased a new CAT Y pipe with both cats, and installed 4 new oxygen sensors. I am still getting the code, so after some research I have found my tahoe is built to California CARB emission standards...so if I understand correctly, the regular federal EPA cats don't meet my computers CARB level emissions.

1) Can I flash my PCM to remove the CARB standards so that I won't have a code?

2) Can I replace my PCM with another tahoe PCM that is non CARB?

Please help...truck runs terrific but this engine light is very depressing after doing manifolds & cats etc.

What brand of cats and O2 sensors did you purchase? Are your exhaust manifolds leaking? Any other codes besides P0420 and P0430?

2007s were a transition year and have some differences in their computer systems compared to the later years.

My truck has California emissions and runs Federal cats (Magnaflow 51578) without issue, been almost 5 years now.

Several years ago, after exhaustive research, I concluded that there was no discernable difference in the tune or the cats between CARB compliant and Federal compliant. In the last year or so, there is a physical difference between the cats along with the price. I put the Federal cats on not knowing that my truck had California emissions.

It is normal for new cats to throw a code once or twice when they are breaking in, the first 100 miles or so. If this is your situation, clear the codes and keep driving it.

 

[Nate07Tahoe]

Hmmmm that would be great…how does this tune happen? No I’m not sure I fixed what took the first cat out…to be honest I noticed when I removed the old Y pipe that only one of the 2 cats had the CAT mesh in it so maybe it only went bad because the material was knocked loose? Anyway, it’s all replaced now including manifolds and gaskets, spark plugs, wires, PCV line, valve cover etc. if a tune will make it happy, I would be ecstatic.

 

[Nate07Tahoe]

What brand of cats and O2 sensors did you purchase? Are your exhaust manifolds leaking? Any other codes besides P0420 and P0430?

Cat is Davico it was $500
Oxygen sensors were all from 1A auto
Did manifolds and gaskets too because I had a tick…they are not leaking for sure.

Cats were done a year ago, I’ve tried spacing the downstream sensors, clearing codes, putting some marvel in the fuel tank etc.

 

[Fless]

What specific codes are setting the money light?

Every measured the temps at the input and output ends of the cats?

What do your long- and short-term fuel trims look like?

 

[swathdiver]

Cat is Davico it was $500
Oxygen sensors were all from 1A auto
Did manifolds and gaskets too because I had a tick…they are not leaking for sure.

Cats were done a year ago, I’ve tried spacing the downstream sensors, clearing codes, putting some marvel in the fuel tank etc.

It is well known by those who frequent these forums that the computer systems do not like aftermarket sensors. If you are getting 420, 430 codes and there are no exhaust leaks then the sensors may be your culprit. If you have the old ones, try swapping in a pair on one side, remember that the upstream and downstream sensors are different.

I do not know of Davico but they seem good and not like cheap Chicom garbage that's made to fail.

 

[drakon543]

you could also have a shop or a friend who has a higher end scanner a look. if your advance or trims are way off or all over the place it could point to another issue.

 

[Nate07Tahoe]

The only code is now P2A01

 

[George B]

Replace that sensor. Bank 1 sensor 2. The Denso units from rock auto are good sensors to use.

 

[Fless]

While you have that sensor disconnected, load test the heater circuit with something like a turn signal bulb, see if it lights brightly when first turning the ignition key to 'run'.

 

[Nate07Tahoe]

Question for you guys…downstream sensors only check emission function of CATs right? If I space them out of the exhaust, it won’t change my fuel ratios or anything right?

 

[Just Fishing]

That won't work, they need to see heat and activity.
Replace both the upstream and downstream sensors with OEM, do them at the same time so you don't end up with other issues.

 

[Nate07Tahoe]

Hi All, replaced one side downstream sensor with a Bosch 15898 and then the CEL code shifted to only the other bank...so I replaced that one with the a Bosch too and I now have no CEL...I guess this confirms previous posts that CARB cats are not different but rather just go through a certification process. So pumped to have a clear dash...thanks all for your support.