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Question about CVN (Calibration Verification Number) on a '05 OBKXT (A2WC522S)


mx5
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The new software in the smog test stations in California started checking the CVN (Calibration Verification Number) and send you to the smog referee if it doesn't match the ones by the manufacturer or if you're running an unique one (compares vs what the machines read from other cars of the same model across the state)

So I started looking towards converting my car to run the stock calibration.

 

It is a manual '05 OBKXT (A2WC522S)

 

Then I got the stock ROM for my car from here and flashed it with Tactrix OP 2/EcuFlash :

http://www.romraider.com/forum/download/file.php?id=5114

 

To check the CVN I used a regular ELM327 reader - OBD2 (and not SSM) to be as close the way the smog station is pulling the info as possible.

 

For software I tried Torque first, but the only smog/calibration info it was showing was the emissions readiness.

 

I searched further and another suggested app for the ELM327 was CarSys.

So I ran it and for my current custom ROM it listed this as the CVN:

21DE1D8C94B81CC1

 

Anyone else with same gen car & running stock software willing to check and post their CVN to compare? Any other programs which show CVN?

05OBXT_manual_stock_A2WC522S_CVN.thumb.png.1b4b8d7a9ab1efc5c2acb7e0fdb64d32.png

20201103_084509.thumb.jpg.58a449188805e554ad249a5c3d531be2.jpg

Edited by mx5
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I just noticed that EcuFlash also shows CVN in the log when loading a ROM.

And for that same stock ROM it shows "CVN: 0091BE32"

That is puzzling - a totally different number than the CarSys output.

 

My car's an LGT but I'm running A2WC522S. I can take a peek, though car's not stock.

My car is not stock either. But the smog check machine needs to see calibration ID and CVN it is expecting

I wish in the OBD-II section along "Force Pass Readiness Monitors" field there was a "Force CVN" one too so I didn't have to take out the ID1050x :)

Edited by mx5
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Why do you think I closed up shop and vacated the state?

 

 

Forcing readiness monitors is a federal offense. Also, it does not work every time. You can force the monitors, but not stop the misfire. I have seen cars fail because the tech noted the obvious misfire and no active or stored codes. Just as an example.

 

 

As for the CVN, how do you know exactly what data Subaru provided to CA? You dont. So, it is going to take some time for owners to gather the info from their own smog tests and report back. Once they have the data and figure out how to manipulate the CVN, the state will have found a way to discover the change. The state made this all VERY clear to shop owners a few years ago. That this new tech was coming and that the state was finally going to be one step ahead of tuners and closer to outlawing all motorsports. They already tried once.

 

 

 

Welcome to COMMIEFORNIA. My best advice is to move to a FREE STATE. I did.

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As for the CVN, how do you know exactly what data Subaru provided to CA? You dont.

Well, BAR posted that starting July 2020, they are pretty much checking all cars manufactured past 2000. Even if for whatever reason they don't have all CVN from the manufacturer for a specific model, it is quite easy for the machine to compare the CVN vs all other smogged cars of the same model across the state. If it is an unique one, it is obvious that something's going on and the machine will send you to a referee to look into what's going on. Keep in mind that they have been logging the CVN information from all smogged OBD2 cars for years, but just not acting on it. Now they just decided they logged enough data to recognize what's what.

 

Once they have the data and figure out how to manipulate the CVN, the state will have found a way to discover the change.

I guess they can do something with the new cars. But not much they can do with a smog station machine hooked to a 15-20 year old ECU which all id information it could report over OBD2 is Cal ID and CVN.

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You can probably try searching for the string being read out by CarSys (and/or the one from ECUFlash) in a hex editor to find the address where it's located, and then compare it to value at the same address on a "stock" copy of your CALID's rom from the RR forums repository.
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You can probably try searching for the string being read out by CarSys (and/or the one from ECUFlash) in a hex editor to find the address where it's located, and then compare it to value at the same address on a "stock" copy of your CALID's rom from the RR forums repository.

 

Good info. Like I said, you dont know what the state has or is using. The CVN could be in an entirely different format than the current tool being used.

 

As the state has now worked with aftermarket tuners and CARB has approved a few tunes, the state has far more info than most realize. My in house tuner was the first to have an aftermarket tune approved by CARB. For the Innovate S/C kit (BRZ/FRS). I have a small bit of inside info most do not.

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An update. With the ROM linked in the first post (supposedly OEM for my car model/year) I just passed smog. I don't know what the exact CVN is, between the EcuFlash (SSM) or CarSys (OBD2) showing different, but whatever it is the smog station OBD2 computer accepted it so the ROM is confirmed good for '05 OBKXT. Because covid I couldn't get closer to the display and film what the machine showed during testing.

 

The engine is converted from the original side feed injector setup to top feed /rails/TGV from a '08-'14 WRX. The OEM WRX blue top feed injectors are slightly bigger than the original OBK side feed ones, but the stock ROM compensates for that without triggering a check engine light/codes.

 

By the way I just noticed the smog database in the Pass/Fail column now has the code D if a car has failed the CalID/CVN check:

https://www.bar.ca.gov/pubwebquery/vehicle/pubtstqry.aspx

smog.thumb.jpg.96edd87d5265695c85881333ee47d126.jpg

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  • 8 months later...

Thanks for posting your experience. I know the future of tuning here in SoCal is looking pretty grim so I'm sure there are more of us that will run into this specific dilemma.

 

 

 

I also have a 2005 OBXT running A2WC522S, however my smog isn't due until later this year. I have been curious how this process would go after flashing to a different rom (A2WC522N), and then back to A2WC522S.

 

 

I just ordered the ELM reader from amazon, I'll report what my CVN is when it comes in.

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  • 8 months later...
I just passed CA smog today using the same tune as OP, downloaded from the same source. 2005 OBXT 5MT. I had previously flashed a modified version of A2WC521N
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