CARB Clean Truck Check Program

The Clean Truck Check, formerly known as the Heavy-Duty Inspection and Maintenance (HD I/M) regulation, subjects nearly all non-gasoline vehicles with a gross vehicle weight rating (GVWR) over 14,000 pounds that operate in California to periodic emissions testing. Analogous to California’s Smog Check program for light-duty vehicles, these testing requirements help ensure that heavy-duty vehicles operating in California remain equipped with properly functioning emissions controls, and when malfunctioning, that these systems get repaired in a timely manner. Through the repair of malfunctioning emissions control systems, the Clean Truck Check will substantially reduce toxic particulate matter (PM, known as soot) and emissions of oxides of nitrogen (NOx, a contributor to smog formation) from the heavy-duty vehicle sector to reduce air pollution and to improve public health across the state, especially in communities disproportionally impacted by heavy-duty truck activity.