Emissions Compliance Testing Requirements for Clean Truck Check
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March 13, 2024
This Fact Sheet presents information on the Clean Truck Check regulation applicable to heavy-duty vehicles operating in California and describes requirements for emissions compliance testing. Emissions compliance testing will become effective October 1, 2024.
Emissions Compliance Testing Requirements
How will I know when emissions testing begins?
Clean Truck Check emissions compliance testing requirements for all vehicles that operate in California are effective October 1, 2024. All vehicle compliance deadlines on or after January 1, 2025, will require a passing vehicle emissions compliance test as part of the compliance demonstration. Vehicles may submit tests no more than 90 days prior to the vehicle’s compliance deadlines.
For example, a vehicle with a compliance deadline of February 1, 2025 may submit a passing emissions test as early as November 3, 2024. Vehicle’s upcoming deadlines will be available in the Owner’s CTC-VIS fleet account.
How often will my vehicles require an emissions compliance test?
Nearly all vehicles are required to undergo twice per year testing with results submitted to CARB.
On-road agricultural vehicles and California-registered motorhomes will only be required to undergo testing once per year.
Three years after the start of Clean Truck Check emissions compliance testing (Oct 2027), on board diagnostics (OBD) equipped vehicles will be required to undergo testing four times per year.
On-road agricultural vehicles and California-registered motorhomes will remain on the once per year testing frequency, even if equipped with OBD.
What are the due dates for my vehicles’ emissions compliance testing?
For California-registered vehicles, the due dates, called compliance deadlines, are linked to each vehicle’s DMV registration expiration/renewal date.
For vehicles registered outside of California and for vehicles exempt from DMV registration requirements (e.g., public agency vehicles, some federal vehicles), compliance deadlines are based on the last number of a vehicle’s VIN as shown in the table below.
Passing Clean Truck Check test results may be submitted up to 90 days before a compliance deadline.
For details and examples please see:
- Clean Truck Check Requirements for Vehicles Subject to Semi-Annual Compliance
- Agricultural Vehicles & California Motorhomes Annual Requirements
How must my vehicles be tested?
The testing requirements depend on whether your vehicle/engine is equipped with OBD or not.
OBD equipped vehicles (2013 and newer diesel engines, and 2018 or newer alternative fuel engines) are required to undergo a scan of the engines’ OBD data using a CARB-certified OBD test device.
Non-OBD vehicles (2012 and older diesel engines, or 2017 and older alternative fuel engines) are required to undergo a smoke opacity test and a visual inspection of the vehicle’s emissions control equipment, referred to in this program as the Vehicle Emissions Control Equipment Inspection. The smoke opacity test is the same SAE J1667 snap acceleration smoke inspection used to comply with CARB’s Periodic Smoke Inspection Program (PSIP). Note that alternative fuel non-OBD vehicles are only required to complete the visual inspection and are not subject to the smoke opacity test requirement.
Other Requirements
Is screening for high-emitting vehicles still in effect?
Yes, high-emitter vehicle screening that began in January 2023 using roadside emissions monitoring devices remains in effect. Even if your vehicle passes its emissions compliance tests, it still may be identified as a potential high emitter in between testing intervals. If you receive a Notice to Submit to Testing (NST), a passing Clean Truck Check compliance test must be submitted to CARB within 30 calendar days of receival. Be sure to follow the instructions in the letter you receive from CARB and don’t wait until the last day to get your vehicle tested and submit test results to CARB. Once CARB determines your vehicle is compliant, there is nothing more you will need to do in response to the NST.
How to get more information about Clean Truck Check
How can I receive updates on Clean Truck Check activities?
Subscribe to receive automatic email updates on Clean Truck Check implementation and other activities.
Where do I get additional Clean Truck Check information?
For more information, visit Clean Truck Check (HD I/M) or Clean Truck Check (HD I/M).
You may also view CARB’s training modules developed for the Clean Truck Check Tester Training Course at Tester Training Course, Exam, and Certification.
Scroll to the Helpful Videos section to view them. These modules provide more in- depth information on the requirements of the Clean Truck Check regulation and testing procedures that may be helpful to vehicle owners.
Where can I find the text of the final Clean Truck Check regulation?
The Clean Truck Check regulation, referred to as the final regulation order, is in title 13, California Code of Regulations, sections 2195 - 2199.1 and is available at Final Regulation Order - Attachment A-1 Heavy-Duty Inspection and Maintenance Program.
If I have additional questions, how do I contact CARB?
Please email staff at hdim@arb.ca.gov. We generally respond within three to five business days.