For gasoline-powered hybrid vehicles and vehicles with stop-start systems, what readiness states are acceptable to complete the liquid fuel leak inspection?

• A. "KOEO" or "Ready"
• B. KOEO
• C. KOER
• D. Engine running

Answer: (A)

When checking for liquid fuel leaks, the test is done with the engine off or in a non-running state to avoid the hazards and variables that come with fuel pressure while the engine is running. For gasoline-powered hybrids and vehicles with stop-start systems, two readiness conditions make sense: KOEO, which means key on and engine off, and Ready, which means the vehicle’s OBD readiness monitors have completed and the system is in a test-ready electrical state even if the engine isn’t running. KOEO ensures the fuel system is powered and accessible for inspection without engine motion, while Ready covers vehicles that may not be running the engine but are still considered test-ready by the diagnostic system. KOER, or engine running, isn’t appropriate because running the engine can alter fuel pressure and flow, potentially masking leaks or creating safety risks. Likewise, “Engine running” is not acceptable for this reason.