Secondary ECU

[SnotRocketRS]

I want to purchase another ECU for my Sonic so I can have a stock one and a tuned one. Does anyone know the parts number and location of the ECU? My car is a 2017 Sonic LT hatch with an automatic 1.4T.

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[YouBeTailsIllBeSonic]

If I'm not mistaken this has been tried and apparently doesnt work......cant remember why.

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[SnotRocketRS]

If I'm not mistaken this has been tried and apparently doesnt work......cant remember why.

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Well damn. Apparently you can do it on the new Veloster Turbos. I was hoping I could do the same

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[skurtov]

Why? Just why? If you have a tune, reflash the stock one and you're good to go. Any new ECU require dealer programming.

 

[SnotRocketRS]

Why? Just why? If you have a tune, reflash the stock one and you're good to go. Any new ECU require dealer programming.

Wouldn't they be able to read that it had been flashed though?

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[skurtov]

Wouldn't they be able to read that it had been flashed though?

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No. Not that I have heard of.


But don't take my word for it, if you need to know for sure, speak with your tuner of choice. If they don't give you a good clear answer then try another one. HPTuners, BNR, Vermont, and Trifecta will all be happy to help.

 

[JTee2017]

Whether GM would be able to see a "reflash" may depend on the model year and ECM.
As of the past few years, a GM technician could and usually would read the ECM for any changes that were made back and forth from a performance to stock program. Assuming there was an issue where a technician was looking for a problem and the customer brought the car in for service.

They are told to check all sorts of things. On our Equinox which has the 3.6L V6 with an Elite Catch Can I installed in it . . . I took the car in for the first "free"oil change and when I checked under the hood after picking it up, there was a big oily thumb print on top of the Elite Catch Can. And. . the catch can is not anywhere near the oil fill cap, oil filter, dip stick or any other part having to do with an oil change. I installed it behind the batter and it isn't very obvious unless you are looking for something.

 

[ScarabEpic22]

The dealer can see if the ECM has been reflashed and the ECMs store mileage...so it's really obvious if it's been swapped out. It used to be easier to buy a spare set of computers, I did for my TBSS, but the later ECMs like ours store mileage and have a flash counter plus you can easily validate the checksum (CVN) against the expected one.

Punch your VIN in on https://tis2web.service.gm.com/tis2web and it will tell you the right CVNs for your vehicle. If a dealer is asked by GM to check if you're tuned, they'll do is hook up the MDI and compare the CVNs, mileage, and flash counter (no clue on the order).