Modern cars have electronic dashboards with digital odometer displays. The car manufacturers use these because they are cheaper to produce than a mechanical dashboard and easier to fit into the car as there is no mechanical speedometer cable. This new technology has its own problems though. Electrical pulses in the cars wiring can cause the dashboard mileage data, which is stored internally on an EEPROM (Electrically Erasable Programmable Read Only Memory), to become corrupted. This corruption could happen for a number of reasons:

• The dashboard may be damaged in a collision or through vandalism.
• The dashboard may develop an electrical fault
• The vehicle battery was discharged and the vehicle had been jump started

In these examples, the corruption of the information held in the EEPROM may mean that the mileage displayed on the speedo is now incorrect and requires a correction. Dashboard correction may also be necessary where a replacement cluster has been purchased, either new or second hand. If it's a new one it will have zero miles on it. If it's a second hand one the mileage displayed is also likely to be different to the original thus requiring correction.