Lexus Repair/1999 Lexus RX300 "drive cycle"
ME wrote at 2014-10-03 01:01:05
Read up on ODB II and Scan tools.
All cars after a date in the late 1980s have to include a computer module to store emission codes etc.
These codes are wiped clean (reset) if you pull the battery or "clear" them with a scan tool.
As you drive the computer begins to collect data used to collect data from sensors. When the car has been operated long enough, (drive cycle) these values are calculated and stored in the computer module.
The person answering above, was referring to older vehicles without the OBD codes.