How easy/common is odometer tampering?

I was looking at a used car whose big selling point was exceptionally low odometer reading for its age. When I saw the car though, I could tell from the condition that there was no way it had only done 58,000kms (which is what the sales listing said). And the CIN (Customer Information Notice) had a big warning that said the odometer was inaccurate.

The salesman made some excuse about how the odometer reading was probably recorded wrong somewhere because of a typo, and because the actual reading didn’t match that record, they had to put that warning there. He assured me that the odometer reading was accurate. But that just didn’t seem feasible.

But that just raises so many questions. Is tampering with an odometer really so common, and easy? It is illegal, I know that much, but if it’s so easily exposed by the CIN, why would they risk it? Is it common, or was that guy just really brave/stupid?

I mean, used car salesman do know the reputation that used car salesman have. Who’s going to believe a used car salesman when he says that what looks like fraud is just a bureaucratic oopsie?

It is very easy to change the odometer that you can see. Not so easy to change the miles stored on other computers in the car.

If the CIN says it is inaccurate, if it looks to you like it is inaccurate, it very likely is, indeed, inaccurate.


For someone who knows how, almost as easy as changing the time on all your clocks at the daylight saving time transitions. The odometer reading is recorded over the years for various purposes, when the car is first titled, first registered, when it is insured, required state safety inspections, emissions tests, when repairs are made, so it is possible in theory at least to verify the odometer whether the reading has always been at least increasing with time, or if it ever decreased, which would mean it was tampered with. The “tampering” may not have been purposely illegal, done to deceive; it might be that the odometer function broke and that part to be replaced, etc.

When buying a used car, the common advice here is to first obtain a pre-purchase inspection done by your own mechanic at your expense. Your mechanic will be able to tell if the odometer reading is reasonable for the amount of wear and tear observed.

Low miles isn’t what I’d be seeking in a used car, at least not as the first priority. I’d rather buy a used car with 100K miles that had been driven 20K miles a year compared to the same car with only 10 K total miles over 5 years. 20K per year means the car was driven mostly on the freeway and that type of driving, constant speed, not much stopping and starting, those are very easy miles on a car. 2 K miles per year, a lot of stops and starts, that type of driving is hard on a car.

Or DoorDash. With people driving Uber now, there are used “taxis” for sale.

Now I don’t know for sure, but it is not easy to roll back an electronic odometer like it was in the old days. But if you get one from the scrap yard it will show the mileage from the junker. Now I thought you could just swap the chip in the eco to show the new mileage but I’m not sure about that. One of the YouTube mechanics always uses his reader to check mileage and is usually a little off from the display, so maybe it is reading the chip.

At any rate sure, the display may not be actual. The may have been a legitimate reason but in minnesota the title needs to indicate that the display is not actual.

Yeah. That’s pretty much what my wife just pointed out. The high miles car could’ve belonged to a courier working 16-hour days. Long distances, yes, but all stops and starts.

I think this is perhaps more relevant in big countries, where everything is spread out, and there are long freeways connecting everything. I am in the big city of a small country. That long consistent freeway driving doesn’t happen here enough to make a difference.

Showing far less miles than the actual is why it is done as it makes a huge difference in the asking and selling price of the vehicle. Very few are ever prosecuted for this in spite of the laws so some may look at it as worth the risk. Odds are they would never go to jail even if convicted.

I worked for a dealer many years ago who would routinely change out instrument clusters on pickups. All of those 150-160k miles trucks would end up on the front row showing 75 or 80k miles with a much higher price tag.

And as for the obvious; I flat refused to have my fingerprints anywhere near those cluster change operations.


Co-worker got a call a few months after her husband sold his Subaru Forester with over 200,000 miles on the odometer, it was back on the market with around 70,000 fewer miles.


I would say that odometer tampering is a lot more common than one might suspect, especially with today’s digital instrument clusters. It is actually much easier to change the mileage on a digital dash than it is on the old-style mechanical odometers.

I have seen many used cars for sale with allegedly low mileage, where the interior and/or engine compartment cosmetic condition just doesn’t jibe with the mileage showing on the dash. Apparently, there are people who will accept the (false) odometer reading, and pay a price premium based upon these (allegedly) low miles.

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Had to re read the book but Jason Vines who was the PR chief for Chrysler and Ford among others went along with a Jeep engineer to investigate unintended acceleration in a Jeep Grand Cherokee that turned out to be caused by a floor mat stuck under the pedal by road salt and other muck. While they had a scanner hooked to the truck it was noticed that the odometer showed 25,000 miles while the computer recorded closer to 70,000 miles. Apparently the Jeep had been bought from a Ford dealer a few months before.

Yeah I said before when we traded our 58 Chevy at the Chev Buick dealer it had over 60k on it. It showed up on the ok used car lot with 28k. The had painted the sand blasting on the hood though so it looked good, if you remember those hoods on the 58.

When mechanical odometers were in use, it was not uncommon, many months and miles later, to start seeing the odometer numbers roll by with pick marks on them. Odometer fixers would visit the local used car lots with their little bag of tools and picks. A small fee would turn a high mileage car into low mileage car.
I’m sure it’s similar today but instead of the little tool kit they probably have a lap top computer.

Maybe a computer expert can illuminate us. I assume the chip is read only. Could the correct software allow access? Just curious.

Yes, there was a demo of resetting the odo with a laptop on one of the car shows a few years ago.

There are some sellers on eBay who sell so called Reman BCMs and require no exchange. That is not to mean that they condone fraud.
They ask for make/model, VIN, the part/code numbers from the BCM, and the current mileage. The replacement is programmed with all of the RPO codes for that particular VIN and of course; the mileage.
No doubt some buyers will lie about the actual miles on the vehicle.

The “chip” cannot be read-only, as the mileage must be updated in real time, as the car is driven. There are various methods of changing the mileage, some more sophisticated than others, including using an interface cable and suitable software through the OBD II bus, replacing the instrument cluster or BCM, etc.

Some cars employ protection features, such as storing the VIN in the instrument cluster, and displaying a mileage of ------ or refusing to update the mileage as the car is driven if the cluster is swapped with a different VIN. Some cars do not employ any sort of protection feature, and a used or remanufactured instrument cluster can be installed and appear to function normally. There are programs which can be used together with a laptop and interface cable to edit the mileage stored in the PCM, instrument cluster, etc.

So easier done than said. I was always in favor of an hour meter but spoke that could just as easily be hacked.

My car fax would show only trans fluid changes and no oil changes even though done every 5000. So that’s no reliable source.

Teenage-me, my boy scout troop purchased an old decrepit-looking car, engine trans ok, so idea was to make a dune-buggy. After removing the body panels, the first thing the we kids did was roll back the speedo, using a bent piece of clothes-hanger wire. Not done w/evil intent, just to see how easy it was to do. Very easy.

If you just wanted to roll it back a little, you could put the rear wheels in the air and let it run in reverse for a few hours. Sub-plot of the 80’s movie Ferris Bueller’s Day Off.

When I was in my teens in the 1960’s in Brooklyn, I had a route on Coney Island Ave. that I would ride on my bike. There was a concentration of car dealers and I would stop into each one and ask the used car manager if he needed any “clocks reset”. When I received a “yes”, which was often, I’d get my picks and other tools out of my backpack and reset odometers to whatever was requested. One day my dad brought home a new tool for me. It was a reversible electric drill, and I immediately realized the possibilities. I went out to my dad’s car, disconnected the speedometer cable, chucked it into the drill, and reduced the odometer by 10,000 miles, in a few minutes. Made my little “clock repair” business a lot easier.