Diesel Smog Check Inspections Beginning January 2010, state law requires certain diesel powered vehicles to be included in the Smog Check Program. This Includes all model year 1998 and newer diesel vehicles with a gross vehicle weight rating for up to 14,000 pounds and less. The diesel vehicle Smog Check consists of an on-board diagnostic test, a visual inspection of the emission components and a visible smog test. If your vehicle fails the Smog Check, you may qualify for financial assistance of up to $500.00 toward emissions-related repairs, or you may be eligible to receive $1000.00 to retire your vehicle. for more info please visit http://www.smogcheck.ca.gov/ or call toll -free 1-800-952-5210