What does KOEO stand for in the context of emissions testing?

In the context of emissions testing, KOEO stands for "Key On Engine Off." This term is crucial for technicians when performing diagnostic tests on vehicles. During KOEO, the ignition key is turned to the "on" position without starting the engine, allowing the vehicle's onboard diagnostic system to run self-tests and monitor various systems, including those related to emissions.

This phase is often used to collect necessary information on the vehicle’s readiness monitors and to check for any trouble codes that might indicate issues with emissions control components. Understanding KOEO is essential for accurate emissions testing, as it helps detect problems before the engine is running and allows for a clearer diagnosis of potential emissions-related failures.

The other options do not accurately reflect the standard terminology or the process used in the emissions testing process, missing the specific focus on the ignition and engine state, which is critical to ensure proper diagnostic procedures are followed.