How is tampering defined in relation to emissions systems?

Tampering in relation to emissions systems refers specifically to making unauthorized adjustments to the fuel or exhaust system of an engine. This encompasses actions that modify the engine's performance in a way that can increase emissions beyond factory specifications. For instance, altering the air-fuel mixture, changing exhaust components, or bypassing emissions control devices fall under this definition. Such actions can compromise the effectiveness of the emissions system, leading to higher pollutants being emitted into the atmosphere.

The other options do not accurately capture the essence of tampering as defined in emissions regulations. Using manufacturer-approved parts is essential for maintaining compliance but does not relate specifically to tampering. Cleaning engine components is a standard maintenance practice that helps ensure optimal performance and does not involve modifying the emissions system. Finally, reducing emissions through the installation of filters is generally considered a lawful and beneficial action rather than tampering, provided the filters meet regulatory standards. Understanding this differentiation is crucial for recognizing practices that preserve the integrity of emissions systems.