Age and mileage of a vehicle are generally not factors when

Age and mileage of a vehicle are generally not factors when it comes to passing an exhaust emissions test. As biglow said that regular maintenance is the most important factor for passing an enhanced I/M exhaust analysis test. Failure of the vehicle owner to replace broken accessory drive belts, leaking AIR pump tubes, defective spark plug wires, or a cracked exhaust manifold can lead to failure of other components, such as the catalytic converter. Tests have shown that if the vehicle is properly cared for, even an engine that has 300,000 miles (480,000 km) on it can pass an exhaust emission test.