Welcome to Carb Clean Truck Check 411 – Your Trusted Resource for CARB CA HD I/M Compliance Information At Carb Clean Truck Check 411, we understand that navigating California's CARB HD I/M diesel emissions regulations can be confusing for vehicle owners. Our website is designed to provide clear, comprehensive information to help you understand the requirements and stay compliant. Whether you're a fleet manager or an individual truck owner, we are here to guide you through the process with expert advice and practical solutions. Let us help you keep your diesel vehicles on the road and in compliance with CARB standards.