California has some of the strictest air quality rules in the United States. This is especially true for diesel truck emissions.
The Clean Truck Check program is an important step in the state’s effort to reduce air pollution and protect public health. For diesel truck owners and commercial vehicle operators, following these changing rules is a legal must. It also helps support cleaner air and more sustainable operations.
People know the Clean Truck Check program as HD I/M, which stands for Heavy-Duty Inspection and Maintenance. Created by the California Air Resources Board (CARB).
Its goal is to monitor and reduce emissions from heavy-duty diesel vehicles. The goal is to make sure that vehicles in California follow current emission standards. This will help lower the state’s greenhouse gas and pollution from small particles.
This program affects all diesel trucks and commercial vehicles. It includes those with a gross vehicle weight rating (GVWR) over 14,000 pounds that operate in California. That includes both in-state registered and out-of-state vehicles that enter California.
The program began its phased rollout in 2023. Key dates include:
In California, any vehicle with a diesel engine and a GVWR over 14,000 pounds is a diesel truck for the Clean Truck Check. This includes many types of commercial vehicles.
Trucks must meet emissions standards set by CARB. These standards vary by model year and engine type. Manufacturers usually design newer trucks to meet stricter standards. Owners might need to update older trucks or phase them out.
All trucks must have a functioning OBD (On-Board Diagnostics) system that can report emissions data. If a truck doesn’t support OBD, mechanics typically require an opacity test. Testing includes:
Depending on the model year and engine technology, authorities may require smog check testing annually or semi-annually. Trucks with newer OBD systems may qualify for self-testing, whereas others must visit certified testing facilities.
Only CARB-certified testing centers are authorized to conduct Clean Truck Check inspections. Many existing smog check stations, truck stops, or specialized inspection sites host these.
The cost of testing can range from $50 to $150 per inspection. Truck owners must provide:
Before heading to a test center, conduct a pre-inspection of the vehicle. This should include:
Frequent causes of failure include:
If your truck fails, don’t panic. Steps include:
Failure to comply can result in fines up to $1,000 per day per vehicle. Repeat violations can lead to escalated penalties and legal action.
Not following the rules can lead to registration holds at the DMV. This can stop vehicles registered in California until someone fixes the problem.
Fleet operators risk operational delays, increased costs, and reputational damage. Authorities can bar non-compliant vehicles from entering certain regions, which affects delivery schedules and commercial operations.
Exemptions and Special Cases
Certain vehicle types are exempt, including:
Trucks that farmers only use or that drive a certain number of miles each year may qualify for testing exemptions. Proper documentation is essential to claim these exemptions.
Preventative maintenance is the best defense against non-compliance. Tips include:
Truck owners should use digital fleet management tools or manual logs to track test dates. CARB’s online portal can send notifications and updates.
Organizations like Clean Truck Check LLC offer consulting, testing support, and compliance services. They help truck owners understand and follow these regulations. Visit Clean Truck Check LLC to learn how their certified technicians can help you. They have partnerships across the country to keep you compliant with smog check testing and other rules.
Staying compliant with regulations is not just about avoiding fines. It also helps support cleaner air and keeps your business running well. The Clean Truck Check is here to stay, and its enforcement will only become more stringent over time.
To stay informed, subscribe to CARB updates, consult with compliance experts, and engage with services like Clean Truck Check LLC. They help diesel truck owners and commercial vehicle operators stay on top with personalized support. They offer mobile inspections and expert advice.
Certified HD/IM Clean Truck Check service—making CARB compliance hassle-free for all fleet sizes.
Contact Us
Global Contacts
© 2025 All Rights Reserved