What technology is commonly used to monitor the performance of emissions systems in modern vehicles?

The technology that is most commonly used to monitor the performance of emissions systems in modern vehicles is On-Board Diagnostics, specifically OBD II. This system provides real-time data about the vehicle's emissions and performance through various sensors and electronic components within the engine and emissions systems.

OMB II is designed to detect malfunctions in the emissions control system and notify the driver through a warning light on the dashboard. It regularly checks parameters such as oxygen levels, engine temperature, and fuel efficiency, ensuring that the vehicle complies with environmental regulations. The data collected by OBD II can be accessed using scanning tools by emissions inspectors, making it an essential component in the smog check process.

Other technologies mentioned, such as touchscreen diagnostics and manual emissions testing kits, do not provide the same comprehensive monitoring capabilities and real-time data that OBD II does. Fuel consumption monitoring systems focus specifically on measuring fuel efficiency and do not typically monitor emissions control systems comprehensively. Therefore, OBD II stands out as the primary technology for emissions system monitoring in modern vehicles.