Are aftermarket emission-control parts permissible during VI?

• A. They are never allowed in VI.
• B. They must be OEM parts only, with no exceptions.
• C. They are permissible if the vehicle owner approves.
• D. They must meet OEM specifications; non-OEM parts often indicate non-compliance.

Answer: (D)

In a Visual Inspection, what matters is that any emission-control replacement parts meet the vehicle’s original emission specifications. Aftermarket parts are permissible if they are certified to meet OEM standards, ensuring the system functions and emissions remain within the expected limits. If a part is non-OEM and not certified to meet those specs, it can indicate non-compliance because it may not perform correctly or fit properly, potentially affecting emissions.

Ownership or consent isn’t the deciding factor—the inspector verifies the part’s certification and compliance with OEM specifications rather than whether the owner agrees with the choice. The idea that only OEM parts are allowed is too strict, since certified aftermarket parts can be acceptable; and the notion that aftermarket parts are never allowed is incorrect.