During a Key On Engine Off (KOEO) test, what is the expected behavior of the Malfunction Indicator Lamp (MIL)?

During a Key On Engine Off (KOEO) test, the expected behavior of the Malfunction Indicator Lamp (MIL) is to come on, stay on briefly, and then turn off. This is part of the vehicle's self-diagnostic system, which checks various electronic control system components when the ignition is turned on but the engine is not running.

When the ignition key is turned to the "on" position, the vehicle’s onboard diagnostics are activated, and the MIL illuminates to indicate that the self-diagnostic systems are functioning. The light then goes off after performing these checks if no faults are detected in the emissions control systems or other monitored components. If there is a problem, the MIL would remain illuminated after the KOEO test until the actual running condition indicates otherwise.

This behavior is crucial for ensuring that the driver is informed of any potential issues that could affect emissions performance, providing a clear indication of whether the vehicle's systems are operating within designed parameters.