This document provides an overview of automotive diagnostic scanners. It explains that scanning diagnostic codes with a scanner can help identify check engine light issues and save money compared to taking it to a shop. It describes how scanners connect to vehicles via OBDI and OBDII ports and can be used to diagnose problems, perform repairs, and optimize performance. The document recommends choosing a scanner based on your needs and teaches how to use scanners to understand diagnostic codes and keep vehicles compliant and roadworthy.