CARB Clean Truck Check Program

The Clean Truck Check, previously referred to as the Heavy-Duty Inspection and Maintenance (HD I/M) regulation, mandates periodic heavy-duty vehicle emissions testing for nearly all non-gasoline vehicles that have a gross vehicle weight rating (GVWR) exceeding 14,000 pounds operating in California. Similar to California’s Smog Check program for light-duty vehicles, these California emissions standards ensure that heavy-duty vehicles are equipped with properly functioning emissions controls. When these systems malfunction, timely repairs are required. By addressing these emissions control issues, the Clean Truck Check significantly reduces toxic particulate matter (PM, known as soot) and emissions of oxides of nitrogen (NOx, which contributes to smog formation) from the heavy-duty vehicle sector. This initiative aims to decrease air pollution and enhance public health throughout the state, particularly in communities disproportionately affected by heavy-duty truck activity.