Reprogramming a digital odometer requires access to the odometer's memory chip, which can be accessed in several ways. Disassemble the dashboard, and reprogram it directly by removing the chip and connecting it to a cable. After reprogramming, resolder the chip back to the mount. Alternatively, attach a serial cable to the serial port in the back of the odometer after dashboard disassembly. For more modern vehicles, the diagnostic plug used by mechanics can also be used to reprogram the odometer.
Reprogramming an odometer to show a lower mileage is considered fraud and can incur both fines, the cost of damage done to the car and attorney's fees for the person who performed the act. Individuals who unwittingly purchase a car with a reprogrammed odometer are left without a correct vehicle maintenance schedule and could experience sudden mileage-related repairs not expected at the supposed mileage. They also experience the hassle of hiring an attorney and dealing with a higher loan interest rate or insurance premium once the true mileage of the car is professed.
To avoid fraud caused by odometer reprogramming, have a trusted mechanic examine the car for signs of wear that indicate a higher mileage. Evidence is often found in spark plugs and wires, which normally require replacing after 100,000 miles; a vehicle with 40,000 miles on the odometer and spark plugs that need replaced is a red flag. Buyers can also choose the protection of a certified pre-owned vehicle, which must pass a rigid inspection to gain a warranty before being sold.