Which component must be inspected as part of the liquid fuel leak inspection?

• A. Oxygen sensor
• B. Catalytic converter
• C. Piston rings
• D. Fuel pressure regulator

Answer: (D)

Liquid fuel leak inspection focuses on parts of the fuel system that can actually leak gasoline. The fuel pressure regulator is a key target because it sits on the fuel rail and uses a diaphragm; if that diaphragm or seals fail, gasoline can leak from the regulator body or its vacuum hose. Detecting leaks here is critical for safety and for passing the visual inspection. The oxygen sensor, catalytic converter, and piston rings are not sources of liquid fuel leaks in this context—the oxygen sensor is part of exhaust sensing, the catalytic converter sits downstream in the exhaust, and piston rings are engine internals that don’t present external liquid fuel leaks.