California Air Resources Board

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Background

In December 2021, the California Air Resources Board (CARB) approved the Heavy-Duty Vehicle Inspection and Maintenance (HD I/M) Regulation, now known as Clean Truck Check, in an ongoing effort to meet air quality standards by ensuring heavy-duty vehicle emissions control systems operate properly throughout the life of the vehicle and necessary repairs are made in a timely manner. Clean Truck Check requires reporting, payment of annual compliance fees, and vehicle emissions testing. Subscribe to email notifications to receive emails about Clean Truck Check (Heavy-Duty Vehicle Inspection and Maintenance) program updates.

Clean Truck Check Requirements

Clean Truck Check applies to almost all diesel, alternative fuel, and hybrid vehicles, with a GVWR over 14,000 pounds operating on public roads and highways in California even if they are not registered in California. This includes government vehicles; motorcoaches; transit, shuttle and school buses; hybrid vehicles; commercial and personal use vehicles; California registered motorhomes; and single vehicle fleets. DMV registration holds will apply to vehicles that do not meet Clean Truck Check requirements.

For more information on which vehicles are affected by or exempt from Clean Truck Check, visit Clean Truck Check FAQs.

Requirements for Vehicle Owners:

Vehicle owners must take the following steps to comply with Clean Truck Check:

1. Report affected vehicle(s) in the Clean Truck Check (CTC-VIS) database system.
   1. The information needed to report in CTC-VIS is listed within the Database Reporting Requirements.
   2. Reporting Resources (CTC-VIS) provides video tutorials and helpful information about the reporting process.
2. Pay annual compliance fee
   1. Payments must be made in CTC-VIS. Payments made in other CARB portals will not be accepted
   2. The compliance fee can be paid by either a debit/credit card or e-check. Paper check mailing will NOT be accepted.
3. Submit a passing emissions compliance test by the applicable deadline.
   1. Deadlines for each vehicle are in the Testing Details tab on the My Entity page in CTC-VIS.
   2. Emissions compliance testing and submission of results must be performed by CARB credentialed testers.
   3. Semi-annual passing test submission are required for most vehicles (See Clean Truck Check Requirements for Vehicles Subject to Semi-Annual Compliance).
      1. Effective October 1, 2027, test submission requirements increase to four times per year ONLY for vehicles equipped with On-Board Diagnositc Systems (OBD). Deadlines will continue to be shown in CTC-VIS.
   4. California registered motorhomes(for recreational and emergency use) and vehicles that meet the agricultural vehicle definition are required to test annually.
      1. Agricultural Vehicles Requirements
      2. Motorhome Requirements

Determining Test Type

The flow chart below describes how a testing method is determined for OBD and non-OBD vehicles:

Credentialed Testers and Testing Devices

Anyone can become a Credentialed Tester by completing the no-cost online credentialed tester training course and passing the exam at the end of the course. Credentials must be renewed every 2 years. If you selected to be listed on the Available for Hire Credentialed Tester List during course registration, your name will be added after you successfully pass the exam. For information on creating a credentialed tester account and more, visit Credentialed Testers & Testing Devices.

To find a credentialed tester in your area, visit Available for Hire Credentialed Testers. 

CARB maintains a list of certified OBD devices and SAE J-1667 smoke meter manufacturers. The current Visual Inspection form for Non-OBD testing is available at Credentialed Testers & Testing Devices.

Requirements for Freight Contractors and Brokers

Freight contractors and brokers must only contract with compliant vehicles or fleets and comply with the record keeping requirements. For more information visit Freight Contractor, Broker – Clean Truck Check Requirements.

Requirements for Ports and Railyards

These facilities have requirements regarding Clean Truck Check compliance status of vehicles and access to their facility. Additional information is available at Requirements for Operations in Seaports and Railyards – Clean Truck Check Requirements.

Enforcement

Roadside Monitoring

Since January 2023, CARB has used roadside emissions monitoring devices (REMD) and Automated License Plate Readers (ALPR) to screen for vehicles that may have high emissions. Vehicles flagged as potential high emitters will receive a Notice to Submit to Testing (NST) from CARB Enforcement. If you have received an NST for your vehicle, please follow the directions in the letter. For more information, visit If You Received a Notice to Submit to Testing (NST) Letter.

Field inspections and Access Restrictions

CARB Enforcement and California Highway Patrol have the authority to conduct field inspections at weigh stations and roadside locations. In addition, non-compliant vehicles may be denied entry into ports and railyards.

DMV Registration Holds

Registration holds are being placed by the California Department of Motor Vehicles (DMV) on vehicles that do not comply with Clean Truck Check requirements, including those with CA DMV-exempt license plates. CARB is actively enforcing legislative mandates that require registration holds due to noncompliance with CARB regulations. If you received a Department of Motor Vehicle Registration Hold – Notice of Incomplete Renewal or a similar DMV notice of non-compliance visit Clean Truck Check DMV Compliance.

Tampering with Emissions Control Systems

Disabling, removing or tampering with emissions control systems may result in violations and fines. Removed or disabled emission control systems can be difficult or impossible to repair.

Additional information can be found at Enforcement of Clean Truck Check HD I/M Regulation.

Additional Resources

More detailed information on the Clean Truck Check program, including fact sheets, Frequently Asked Questions, and video tutorials, can be found at Clean Truck Check (HD I/M).

For answers to your specific Clean Truck Check questions, contact hdim@arb.ca.gov.