# How common (and difficult) is rolling back a for-sale car's odometer? **URL:** \ **Category:** Factual Questions\ **Created:** [December 30, 2004, 7:24pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292 "2004-12-30T19:24:32Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [December 30, 2004, 7:24pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/1 "2004-12-30T19:24:32Z")
I’ve been helping a young gal at work locate a better car and she’s quickly settled on eBay, (though I’m not sure why). While the prices look pretty good, I wonder about cars with unusually low mileage. I’m talking about, say, 9-year-old cars with 65,000 miles, etc. Though odometer scams were once commonplace–North Carolina being a real hotspot–is this type of fraud still prevalent? Short of obtaining service records, is there any definitive way to gauge a car’s real usage, short of eyeballing the brake pedals for excess wear, etc? Many of these cars are being sold by smallish used car lots. I’m suspicious of any sales manager who claims to routinely sell lower than market value, “just to move this car off my lot.” (If the car is such a good deal, I ask myself, why isn’t it being sold in the seller’s home town.) My concern for my colleague is that she could buy a car with 50,000 miles more than the odometer says. Any guidance is appreciated. ---
**Author:** ![Alvis](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alvis](https://boards.straightdope.com/u/Alvis)\ **Post date:** [December 30, 2004, 7:27pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/2 "2004-12-30T19:27:19Z")
Get a CarFax report. When looking at several cars with their reports, I was able to note one or two that had their odometers rolled back. ---
**Author:** ![Ignatz](https://avatars.discourse-cdn.com/v4/letter/i/3be4f8/32.png) [@Ignatz](https://boards.straightdope.com/u/Ignatz)\ **Post date:** [December 30, 2004, 9:01pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/3 "2004-12-30T21:01:34Z")
I hope you get a definitive answer on this. Not how to, but the facts on feasibility. I went to a brand name dealership to look at a particular used model. I asked the salesman (who ran after me when I showed up) if I could see one of the cars of interest. He got the key to one and I got in. I said, oh, it’s got an electronic (lcd) odometer. I hear that thay can’t be rolled back, right. He did not answer. I turned the key in the ignition to read the mieage. It said 25000. Nuff said. Or, I mean, how stoopid to roll it back to an even 25,000. Wow! I didn’t buy it. ---
**Author:** ![RogueRacer](https://avatars.discourse-cdn.com/v4/letter/r/7ab992/32.png) [@RogueRacer](https://boards.straightdope.com/u/RogueRacer)\ **Post date:** [December 30, 2004, 9:12pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/4 "2004-12-30T21:12:16Z")
I would look at local used cars personally. Maybe they are all sold now, but I know there was a problem earlier this year about hurricane damaged (flooded) cars being taking out of Florida and then sold (on eBay) from places that weren’t hit. I would never buy a car without seeing it in person and driving it first. ---
**Author:** ![jayjay](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jayjay/32/6765_2.png) [@jayjay](https://boards.straightdope.com/u/jayjay)\ **Post date:** [December 30, 2004, 9:12pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/5 "2004-12-30T21:12:26Z")
> [@Ignatz](#): > > I hope you get a definitive answer on this. Not how to, but the facts on feasibility. > > I went to a brand name dealership to look at a particular used model. I asked the salesman (who ran after me when I showed up) if I could see one of the cars of interest. He got the key to one and I got in. I said, oh, it’s got an electronic (lcd) odometer. I hear that thay can’t be rolled back, right. He did not answer. I turned the key in the ignition to read the mieage. It said 25000. Nuff said. Or, I mean, how stoopid to roll it back to an even 25,000. Wow! I didn’t buy it. Actually, the probability of it being an even 25,000 is just as likely as the probability of it being 24,914. We just give more significance to “neat” numbers like 25,000 than they really hold in the objective world. ---
**Author:** ![Roches](https://avatars.discourse-cdn.com/v4/letter/r/bc8723/32.png) [@Roches](https://boards.straightdope.com/u/Roches)\ **Post date:** [December 30, 2004, 9:32pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/6 "2004-12-30T21:32:07Z")
jayjay: True, but someone who was entering a fake mileage into a car computer’s memory would be more likely to enter a round number than 24,914, because of the significance attached to round numbers. It’s probably just stored in CMOS or EEPROM, and so it could be rolled back if they could access the memory. It might be even easier than rolling back a mechanical odometer since many of those have some mechanism that spoils the odometer if you try rolling it back (such as making lines appear between the numbers). Getting a report is a good idea, and it’s probably good to mention that you intend to get reports when you’re looking at cars. You might be nudged away from cars that have dirty secrets. ---
**Author:** ![qubed](https://avatars.discourse-cdn.com/v4/letter/q/f07891/32.png) [@qubed](https://boards.straightdope.com/u/qubed)\ **Post date:** [December 30, 2004, 9:53pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/7 "2004-12-30T21:53:16Z")
> [@jayjay](#): > > Actually, the probability of it being an even 25,000 is just as likely as the probability of it being 24,914. We just give more significance to “neat” numbers like 25,000 than they really hold in the objective world. Yes, but the probability that it lands on a ‘neat’ number is much, much less than the probability that it lands on a ‘non-neat’ number. There are a lot more ‘non-neat’ numbers that ‘neat’ numbers. And since ‘neat’ numbers hold more value in our perception of them, it’s more likely that the dealer rolled back to the ‘neat’ number than it actually landed on it by circumstance. ---
**Author:** ![jasonh300](https://avatars.discourse-cdn.com/v4/letter/j/46a35a/32.png) [@jasonh300](https://boards.straightdope.com/u/jasonh300)\ **Post date:** [December 30, 2004, 10:08pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/8 "2004-12-30T22:08:48Z")
Seems to me that if I was gonna roll back an odometer, I’d roll it back to a non-neat random number…preferably with lots of 7s in it. Just like when people make up statistics off the top of their heads…it sounds more believable when you don’t use an even number ending in zero. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [December 30, 2004, 10:29pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/9 "2004-12-30T22:29:27Z")
The following might be interesting: > [@](#): > > Jack Gillis / Author The Car Book: “People mistakenly think digital odometers can’t be rolled back, but the fact is, there are products sold over the Internet that would allow anyone who would want to rollback even a digital odometer.” > > SOURCE: [http://www.kovr13.com/02feb02/022802g.htm](http://www.kovr13.com/02feb02/022802g.htm) > [@](#): > > A dealer pockets an additional 10 cents profit for each mile rolled back on a car’s odometer. Ten cents for each mile may not sound like much, but it adds up quickly. > > Roll back 20,000 miles off an odometer and the price of the car gets bumped up $2,000. That’s an extra two grand for the dealer. Take 40,000 miles off a car and dealer might pocket an extra $4,000 or more. > > The National Highway Traffic Safety Administration estimates that odometer fraud costs Americans more than $1 billion in inflated car prices a year. That number does not include inflated financing, insurance and tax costs, additional repair costs, or consumers’ anger and frustration at being cheated. > > SOURCE: [Don’t get flattened by a used car with a rolled-back odometer](http://www.bankrate.com/brm/news/auto/car-guide/odometer.asp) ---
**Author:** ![sqweels](https://avatars.discourse-cdn.com/v4/letter/s/f19dbf/32.png) [@sqweels](https://boards.straightdope.com/u/sqweels)\ **Post date:** [December 30, 2004, 10:39pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/10 "2004-12-30T22:39:47Z")
When you’re rolling back the 1000s rotor on a mechanical odometer, wouldn’t it “catch” on the 3 lower rotors when the 0s lined up, forcing even 1000s unless you spin the others forward to add some miles back on? ---
**Author:** ![sqweels](https://avatars.discourse-cdn.com/v4/letter/s/f19dbf/32.png) [@sqweels](https://boards.straightdope.com/u/sqweels)\ **Post date:** [December 30, 2004, 11:02pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/11 "2004-12-30T23:02:14Z")
On second thought, they would be the _same_ digit across as board as the one you settled on (probably in the 10,000s), wouldn’t they. ---
**Author:** ![hightechburrito](https://avatars.discourse-cdn.com/v4/letter/h/f6c823/32.png) [@hightechburrito](https://boards.straightdope.com/u/hightechburrito)\ **Post date:** [December 30, 2004, 11:10pm UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/12 "2004-12-30T23:10:35Z")
My friend had an Acura Integra, I believe it was a late nineties model, that he could easily disconnect all of the different instrument panels. It was very easy to run the car for miles and miles without the odometer changing at all. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [December 31, 2004, 1:33am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/13 "2004-12-31T01:33:20Z")
The simplest way to roll back an analogue odometer is to hook its cable to an electric drill and rewind it. Digital odometers can be rolled back, but what most people don’t know is that there’s a “hidden” odometer in the car’s ECU. This is much tougher to roll back and most dealers do not have the equipment to do it. This odometer value can be read through the OBD port. ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [December 31, 2004, 1:37am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/14 "2004-12-31T01:37:00Z")
> [@Dog80](#): > > This odometer value can be read through the OBD port. Is this something a car buyer could do, before closing the deal? What kind of equipment is needed? ---
**Author:** ![Alvis](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alvis](https://boards.straightdope.com/u/Alvis)\ **Post date:** [December 31, 2004, 1:55am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/15 "2004-12-31T01:55:29Z")
> [@Carnac the Magnificent!](#): > > What kind of equipment is needed? It depends on the make of the car, but usually a simple cable, a laptop, and software. You can hack up a cable yourself, but I’ve yet to find cheap software. Then again - what is knowing the mileage worth to you? ---
**Author:** ![stockton](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@stockton](https://boards.straightdope.com/u/stockton)\ **Post date:** [December 31, 2004, 2:01am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/16 "2004-12-31T02:01:27Z")
> [@Carnac the Magnificent!](#): > > …While the prices look pretty good, I wonder about cars with unusually low mileage. I’m talking about, say, 9-year-old cars with 65,000 miles, etc. > … Just for the record, I drive an Altima bought brand new off the lot (with 6 miles on the odometer) in 1995. It currently sports less than 61,000 miles. I live downtown, work downtown, have a motorcycle and take public transit whenever I can. I only put a few miles a day on it (if I drive it at all) unless we’re on a trip (and my wife doesn’t drive!). It can happen. No rollback here, just a very beat-up old ‘new’ car. ---
**Author:** ![ZebraShaSha](https://avatars.discourse-cdn.com/v4/letter/z/eada6e/32.png) [@ZebraShaSha](https://boards.straightdope.com/u/ZebraShaSha)\ **Post date:** [December 31, 2004, 2:05am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/17 "2004-12-31T02:05:37Z")
> [@Alvis](#): > > It depends on the make of the car, but usually a simple cable, a laptop, and software. You can hack up a cable yourself, but I’ve yet to find cheap software. Then again - what is knowing the mileage worth to you? Cheaper prices, knowledge of when the transmission might “give”, how honest the dealership is, etc. ---
**Author:** ![Alvis](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alvis](https://boards.straightdope.com/u/Alvis)\ **Post date:** [December 31, 2004, 2:14am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/18 "2004-12-31T02:14:09Z")
No, yeah, you’re right - sorry if I made it seem like I thought it wasn’t worth it. If your suspicious, invest a couple hundred in peace of mind. ---
**Author:** ![KP](https://avatars.discourse-cdn.com/v4/letter/k/a9adbd/32.png) [@KP](https://boards.straightdope.com/u/KP)\ **Post date:** [December 31, 2004, 2:15am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/19 "2004-12-31T02:15:55Z")
The OBD port is in the passenger compartment, and looks like a 16-line version of the Centronics connector that was used on some parallel printers. While you can buy readers (or even rig your own from a laptop with a serial port), it’s one of those “if you have to ask, the answer is NO” things. However, I wouldn’t buy a used car without taking it to a mechanic who specializes in doing used car inspections (A good, trustworthy mechanic may only _think_ they know everything to check, and how to do it efficiently – more experience allows them to be more thorough in the limited time allotted to an inspection: you’re not going to get [or want to pay for] a full afternoon of tear-down) Your mechanic should read the OBD port anyway. It’s been years since I bought a used car, but twice the stored OBD [or its predecessor] error codes alerted me to issues that hadn’t turned up in the test drive. It stores the last (3?) malfunctions or errors (until reset) which can give you a broader view than just your test drive. ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [December 31, 2004, 5:51am UTC](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292/20 "2004-12-31T05:51:26Z")
I had a 1980 Volvo wagon, with (obviously) a mechanical odometer. By the time the car was about 16-17 years old, the odometer would just stop turning for a while. Sometimes a couple hundred miles, sometimes not very much. Then, eventually, it would start again. I had no idea why and, to be honest, I wasn’t really all that interested in trying to fix it. [Next page](https://boards.straightdope.com/t/how-common-and-difficult-is-rolling-back-a-for-sale-cars-odometer/282292.md?page=2)