ECU re-flash/reprogram

MSITTLE5

MEMBER
2003 NISSAN ALTIMA
3.5L
6 CYL
2WD
AUTOMATIC
200,000 MILES

So, I had a locksmith program a new key and got me out of lock mode. Then I got a new ECU and I was going to have the locksmith program it for my key. They wouldn't do it. They said I had to go to the dealer. My understanding is they won't do it because the new ECU has a different VIN on it. Okay, so it wouldn't have my VIN when I smog it. That's why it has to be reprogrammed correct? Because I'm thinking I'll just call another locksmith and not tell them it's a new ECU, just a new key. Or maybe I'll have them supply the key. Either way just program a new key to the new ECU. He won't know the VIN's don't match. But so what. I can register it in another county that doesn't require a smog and no one will know the difference, right?
Please help.

3 Replies

I-SMOGEM

MECHANIC
118 POSTS

Hi MSI.

The Smog Check inspection machine doesn't read, and doesn't care about, the VIN number in your vehicle computer during an inspection. The VIN and License Plate are entered into the inspection machine by the tech for it to correspond to the DMV data base. The Smog Check machine is connected to the vehicle via the ECU connector to read it for trouble codes and completed vehicle diagnostic parameters and that's it! If those have issues, then it may not pass.

Don't stress the issue of what the VIN is in the replacement computer for a Smog Check. If the (reprogrammed) replacement computer matches your vehicle type and engine operation for proper performance and emissions, that's the main thing for a Smog Check. If the emissions are within spec, functional tests pass, visual passes, there are no codes, and the required self-tests are done, then it's no different than any other test you've had in the past.

What you 'might' consider is a "Pre-test" mode inspection considering your concerns. It is a normal test, but "unofficial". If there are issues, then in reality, the State doesn't care. If it does pass though, you will need to pay again for the Official test.

Hope this helped you with your concerns. Glenn

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Sunday, November 22nd, 2020 AT 6:53 PM

MSITTLE5

MEMBER
11 POSTS

Really? Hmm. Okay, so does anyone know why they say a new ECU needs to be re-flashed/reprogrammed in order for it to work? I know the key must be programmed for NATS/NCIS. I contacted a place out of Florida I think, and they said the sell ECU plug and play programmed to my VIN. I just got an ECU from picapart and other than needing to be programmed to a new key why do I have to take it to the dealer?

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Sunday, November 22nd, 2020 AT 8:57 PM

I-SMOGEM

MECHANIC
118 POSTS

Hi again.

(1) Does anyone know why they say a new ECU needs to be re flashed/reprogrammed in order for it to work? There are differences with each year, model, motor, components, etc, for every vehicle that needs to have it's proper operational programming, and there may actually be an upgrade to the ECU programming even if it's a perfect match. Your vehicle may start - run - go - but may not actually operate properly without reprogramming.

(2) Do I have to take it to the dealer? That would be the best choice because they are set up with the best equipment and manufacturer data for the reprogramming an ECU, but there is so much available now that many shops can do it.

Now, to back up to your initial concerns about the Smog Check inspection. I will reinforce the idea of a "Pre-test" inspection. If you replaced the computer for a key issue, and that issue is resolved (it starts), then a pre-test smog inspection will likely let you know if the ECU has performance/operational/emissions issues. And since you haven't stated any performance problems, then I would guess it appears to be okay.

Again, I hope this helps you with your concerns. Glenn

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Sunday, November 22nd, 2020 AT 10:25 PM