Which systems must be inspected with the engine running?

The correct response indicates that both the exhaust and crankcase ventilation systems must be inspected with the engine running because certain aspects of their functionality can only be accurately assessed during engine operation. The exhaust system is responsible for directing harmful gases away from the engine and passenger cabin, and running the engine allows inspectors to evaluate exhaust flow and emissions output. It also helps to identify leaks or obstructions that might only present themselves when the engine is under operational conditions.

Similarly, the crankcase ventilation system, which helps maintain proper pressure within the crankcase and prevent the buildup of harmful gases, requires engine operation for a proper inspection. When the engine is running, it allows for the assessment of air flow through this system, ensuring that it is effectively returning vapors to the intake system and not releasing them into the atmosphere.

Therefore, inspecting these systems with the engine running ensures a thorough and accurate evaluation, as opposed to inspecting them while the engine is off, which would not provide insight into their operational effectiveness.