Popular repair tips from the Car Doctor
Resetting the check engine light after a service
The computer system in the car continually monitors individual emission components. When the battery is disconnected these monitors revert to "not ready" status. The readiness monitors will remain until the car has been driven long enough for the computer to evaluate the various system and sensors. The amount of time can vary based on the vehicle. In some cases it can take up to 100 miles for all of the computer monitors to completely reset.