When diagnosing high emissions issues, which mode allows a technician to view the results of O2 sensor tests?

The correct choice relates to the operation of O2 sensors, which are crucial in diagnosing high emissions issues due to their role in monitoring the oxygen level in the exhaust. Mode 5, specifically, provides the technician with a live data stream and specific test results from the O2 sensors. This mode is used to perform O2 sensor tests, allowing for a detailed analysis of the sensor's performance and ensuring that the readings align with expected norms.

Using Mode 5 is vital for effectively determining whether the O2 sensors are functioning correctly within their designated parameters, which can help identify potential issues contributing to high emissions. By reviewing the live data from the O2 sensors, technicians can make informed decisions about necessary repairs or adjustments to the vehicle's emission control system.