What could happen if a vehicle's emissions control system is modified?

Modifying a vehicle's emissions control system can significantly impact its emissions performance, often leading to increased pollutant output. Such alterations may disrupt the original design intentions of the emissions control components, resulting in the vehicle potentially failing its smog check. The smog check is designed to ensure that vehicles meet specific emissions standards as mandated by law. If the modifications lead to higher emissions than those allowed, the vehicle won’t comply with the necessary criteria, thus resulting in a failure during testing.

When a vehicle fails its smog check due to emissions control modifications, it typically requires repairs to restore compliance before it can pass the inspection and be legally driven on the road. This reinforces why maintaining the integrity of the emissions system is crucial for both compliance with regulations and the environment.