How is an emissions test done in California?
How is an emissions test done in California? Performing Emissions Testing in California. During a smog check, your vehicle will be inspected for its emissions and a visual and functional inspection will also be performed. During the emissions test, measures will be taken to see how much CO, CO2, HC, O2 and NOx your vehicle emits. What causes a car to fail the emissions test? More common trouble codes that cause vehicles fail on emissions test and make the Check Engine light coming on can found below. Even fouled or the worn out catalytic converter is the most cause failed...