Last Updated on November 4, 2022 by SogouAuto
A number of things could cause your car to fail an emissions test. The most common reason is a simple problem with the gas cap; if the gas cap isn’t screwed on tightly enough, it can cause your car to “leak” gasoline vapors, which can contribute to air pollution. Another possibility is a problem with the evaporative control (EVAP) system, which is responsible for capturing and storing fuel vapors until they can be burned off by the engine. A faulty EVAP system can allow vapors to escape into the atmosphere.
Other potential causes of emission test failures include a dirty air filter, a malfunctioning oxygen sensor, or a problem with the catalytic converter. In some cases, the cause of the problem may not be apparent without further diagnosis; for example, a car that fails an emission test because of high levels of carbon monoxide might have an internal engine problem that needs to be repaired.