How does the inspector use the onboard diagnostics (OBD) during testing?

The inspector utilizes the onboard diagnostics (OBD) system during testing primarily to retrieve and analyze diagnostic trouble codes (DTCs). This process involves connecting a diagnostic scanner to the OBD port of the vehicle, which allows the inspector to access information about the vehicle's performance and emissions system.

The OBD system continuously monitors various sensors and components within the engine and emissions control system. When it detects a malfunction or a component operating outside its normal parameters, it generates a DTC, which serves as a diagnostic guide for the inspector. By examining these codes, the inspector can identify specific issues affecting the vehicle's emissions performance and determine if the vehicle is compliant with regulatory standards.

This approach is crucial because it enables the inspector to pinpoint problems that may not be apparent through visual inspections alone, making the testing process more efficient and effective in ensuring that vehicles meet emission requirements.