When performing a visual inspection, inspectors are prohibited from entering Not Applicable for an emission control system that...

• A. Is required for the vehicle undergoing inspection
• B. Is optional for the vehicle undergoing inspection
• C. Not Applicable is not permissible for a required emission control system
• D. Has not been installed yet

Answer: (C)

Not Applicable should not be used for a required emission control system during a visual inspection. When a system is required on the vehicle, inspectors must document the actual status of that system—whether it’s present, functioning, missing, damaged, or otherwise non-compliant—rather than marking it as not applicable. Using Not Applicable for a required component would obscure issues that could affect compliance and the test result.

Not Applicable is appropriate only for systems that do not apply to the vehicle or are not part of its emission control in a given configuration. The other options describe different situations (whether the system is required, optional, or not installed) but do not capture the rule that the status cannot be Not Applicable for a required system.