Pre-2013 model-year engines without OBDs will be required to submit an opacity test and a visual/functional inspection twice a year. The opacity test must be up to the SAE J-1667 opacity standard.

A truck undergoes a Periodic Smoke Inspection Program opacity test in Buellton, Calif. (Beryl Technologies via Twitter) Also, CARB randomly audits fleets, reviews on-site maintenance and ...

But again, the new date for submitting opacity test has been extended until March 31, 2008. The acceptable opacity standards are equivalent to those the provincial AirCare On-Road Program: 55 percent ...