What could indicate the need for a Smog Check after a vehicle has undergone significant repairs?

The need for a Smog Check after significant repairs is particularly triggered by any modifications that may alter the vehicle's emissions controls. When a vehicle undergoes repairs that impact the exhaust system, engine, or any components related to emissions, it can change how the vehicle complies with environmental regulations. This includes changes that might affect how pollutants are managed and can lead to increased emissions.

For instance, if a technician replaces the catalytic converter, alters the fuel injection system, or makes modifications to the air intake or exhaust system, these changes can directly influence the vehicle's ability to control emissions. Therefore, a Smog Check is necessary to ensure that the vehicle still meets California's stringent emissions standards after such modifications.

Other actions like changing a tire, installing new windshield wipers, or repainting the vehicle do not impact the emissions control systems. These types of repairs are cosmetic or don’t affect the vehicle's operation concerning emissions, thus not warranting a Smog Check.