Kind of long story but will make it brief and there is hope. My son bought a used Honda Civic SI from dealer wholesaler in December and been pretty good little car with plenty of warranty. Daughter in law also purchased a Caddy CTS from them, they come with carfax and have had inspections at their service centers before shipping to dealers. Okay now the story. My son bought a new scanner for vehicle ECM's since in laws or someone always has a issue. He was tinkering with it and plugged it into his Honda just getting rundown on it when he punched up his odometer readings. His ECM read different from the gauge cluster by about 15000 miles! The ECM is where they take the reading if it goes to dealer for warranty work and this would put his car just under miles before it runs out! There is also the legal aspect of documentation saying correct miles plus value of a car with warranty still valid is issue. We called where he bought it and being out of town we took road trip to them (2 hours away) along with his scanner incase we were looking at something wrong. Their service dept. didn't even have scanner that could go that deep in ECM to see the issue! We talked with them and they are calling cooperate and will get back to us but they admitted that is not good thing and possible they are going to buy car back with full refund including finance charges, payments made, and improvements(window tint, ect.) plus fuel for drive up to discuss this and cost of or meals for the day...and see about another ride for my son at same price range. Will keep you posted on how this works out but I already have pages printed up on odometer fraud laws and responsibilities which I'm sure they are aware of. It is major pain for a person to legally sell car with gauge cluster not matching ECM! The balk on this I may have to get lawyer and then it will cost them more! May even see about the Grand Sport they have on the lot in a settlement! They did seem honest in concern and have been open to idea of doing things right so will see.

They are offering the moon hoping you don't hire a lawyer. Odometer fraud is serious. You have their family jewels in the channel locks.

Hope you get it worked out to your satisfaction… sounds like a mess.

Are you looking for money or criminal vharges

This is why I only buy new vehicles.

Is the odometer digital? How would they roll it back?

Heck, I didn't know that you could roll back digital odometers.

Digital stuff can be reprogrammed.

Bought a used (3 year old) 1 ton chevy for a ranch truck years ago and cluster went out in dash. Took it to Chevy house and they sent it off and had to calibrate to original miles that were on ECM. Service manager said some could put whatever they wanted on mileage shown but computer they couldn't unless they changed the whole system out.

Pull up the car-fax and look at the service records. They may also help to prove your case. It was probably not done at the dealership but more likely the person who traded it in.

I once had an individual put different parts from a salvaged XLT Ford pickup on an XL. I appraised over 40 cars that Saturday and missed it. Two years later the guy that bought it tried to trade it in and their appraiser caught it. I ended up paying the difference to the owner and know he never believed me. I then contacted the proper authorities and the crook was charged and convicted. Mistakes happen.

Where my BS meter starts singing is when they said their scanner doesn’t even go that far to check the odometer Most cheap o scanners can find that info so I’d say their lying about that for sure. I’d do a little investigating and see if you can get an idea when it was rolled back, if it was an honest mistake I doubt very seriously they’d be offering the moon like they are so it all sounds sketchy to me. Keep us posted on the outcome but if they rolled it back I’d be driving something home for free and I doubt they’d give much of an argument about it.,

Sorry, I understand that. it just seems odd that anyone can do this and you can get the display to show different than the computer has logged.
Sure anything can be hacked, but I would think it should be protected better than that.

It would be cool if the computer logs the times when this kind of setting is changed.

I used a lighter.

Some years ago, I bought a nice used Ford Explorer from a couple of guys who had a dealers license, but no car lot. When I was cleaning out the glove box, I found a service receipt with mileage shown that was more than what was on the odometer. I filed a complaint with the State. Within a week, I was contacted by the sellers, offering to buy the car back. I told them I wanted to keep the car, I just wanted a reduced price for the additional mileage. I had their attention; I named a figure. A day later, we met and I walked away with cash in hand. I don't know what happened after that. When I sold the car later, I told the buyer what I believed the correct mileage to be.

This is not hard to understand nor uncommon. The reading on the odometer is generally saved in the memory of the device that displays it (or another remote module). It counts up off the speedometer. Since disabling the speedometer causes all kinds of other issues (transmission shifting, ABS, traction control, air bags) most crooks just come up with a way to disable the instrument cluster itself so the other modules still read vehicle speed. This is more difficult now than it used to be with modern high speed CAN buses, etc. wired in a loop. Break the loop and all the modules begin to fail to communicate.

Other modules that store odometer do it on their own in most cases. It's not what is displayed and it's very common for a run of the mill wholesaler without link to one brand to have a generic scanner that does not read every bit of data on every car made.

More common than the above is simply swapping out the IPC with another like part from a similar vehicle with lower miles. Sure, perfect functionality would require the VIN in the IPC to match all the other modules AND that the IPC have the specific firmware to operate with that specific vehicle. But it does not have to match in many cases to get reasonable functionality.

It is VERY rare for a dealer to be able to "program miles". One good example above is the 03-06 GMT800 trucks. The CAN system was redesigned in 2003 then slightly again in 2004. Replacement IPC's from the rebuilder have to have both the odometer set and the firmware installed at the dealer level. The dealer can actually get that stuff pre-installed by the rebuilder but as a tech I have seen them mess it up enough to ask to let me do it in house upon installation.

Outside of that example, most modules are programmable for software updates and only if the current version of software has a revision. None of the parameters can be changed by dealer equipment. That requires aftermarket equipment and licensing for the specific purpose yet I doubt very seriously those software suites allow odometer reprogramming. GM doesn't let us go backwards on software. The newer the vehicle, the tighter all these "rules" are.

All that being said, the IPC was likely swapped by a previous owner and not the seller but it's the seller's problem now.

As I read this thread, I was wondering if the opposite had happened. Original IPC, but replacement ECM with higher miles from a salvage yard donor.

Were you paying attention, to the 2020 election. ???

Get the vin number and go to this site. https://www.mytxcar.org/TXCar_Net/SecurityCheck.aspx
There is a record of the mileage every year when it was inspected. Texas cars only.

That is a nifty link.
For kicks I checked out my truck. It would sure help if the inspection shop entered the mileage each year.

If it's a legitimate inspection the mileage is entered when the inspection is done
It's on the paperwork the inspector hands you when your inspection is completed

We aren't after money or burning somebody just want it made right, gauge clusters can be replaced changed and buy a newer or different one from Amazon or Ebay.The ECM doesn't catch alot of changes in program. Would have to go through steps to get bonded title to sell vehicle after this point, the dealer knows they are in the wrong so maybe that will motivate them to fix this situation.