CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Emissions

how can one build up emmissions on an un registered/uninspected car? shop says it has to be driven at various rates of speed over many miles.

It depends on the vehicle. If the battery was disconnected, the computer can lose it’s adaptive memory. When that happens. the vehicle must driven through a drive cycle to reset the monitors.

But like I said, it depends on the vehicle.

Tester

You get the one day permit from DMV, use an OBD 2 scanner. If the drive cycle is complete, the scanner should not show any codes, or indicate that the drive cycle is incomplete. If you erase all codes, all indicator lights will be flashing, leave scanner plugged in and drive until the scanner stops flashing any lights. The scanner manual will describe it better.