Schedule CARB's Clean Truck Check testing for trucks, buses, diesel motorhomes, or entire fleets. Our credentialed technicians provide 24/7 mobile service throughout Southern California.
Please Note: Regulations are subject to change. For the most up-to-date requirements, we recommend visiting the official CARB website.
California’s Clean Truck Check program establishes testing and reporting requirements aimed at reducing emissions from heavy-duty vehicles. This comprehensive guide outlines everything fleet operators and vehicle owners need to know to understand the program and maintain compliance.
Clean Truck Check is a regulatory program developed by the California Air Resources Board (CARB) to reduce emissions from heavy-duty vehicles operating in California. The program requires trucks with a gross vehicle weight rating (GVWR) over 14,000 pounds—including both in-state and out-of-state vehicles—to undergo regular emissions inspections.
Instead of traditional smog checks, Clean Truck Check uses a combination of:
Electronic onboard diagnostics (OBD) testing
Smoke opacity testing (for certain engines)
VIN-based compliance reporting
The goal is to identify and reduce excessive emissions from diesel and other heavy-duty vehicles, helping California meet its clean air standards. Non-compliance can result in fines, DMV registration holds, or other enforcement actions.
Clean Truck Check applies to commercial fleets, owner-operators, and any applicable vehicle that operates on California’s public roads, regardless of where it is registered.
Although heavy-duty vehicles account for just 3% of the vehicles on California’s roads, they are responsible for more than half of the state’s smog-forming emissions and fine particulate pollution, according to CARB. By enforcing stricter emissions regulations, the state aims to significantly reduce air pollution and improve overall air quality.
More formally called Heavy Duty Inspection and Maintenance (HD I/M) — Clean Truck Check is an emissions-reduction program for diesel and alternative fuel heavy-duty vehicles with a gross vehicle weight rating (GVWR) over 14,000 pounds. HD I/M applies to the trucks, buses, and motorhomes that create a majority of the emissions on the road.
The heavy-duty vehicle types shown below are not subject to the regulation:
Deadline: January 31, 2024
Details: Vehicle owners were required to complete initial fleet reporting and pay the 2023 compliance fee by this date.
Start Date: April 1, 2024
Details: Beginning April 1, 2024, vehicles must undergo periodic emissions testing. For the 2024 calendar year only, vehicles subject to semiannual compliance testing are required to test only once. Starting in the 2025 calendar year, these vehicles will have two compliance deadlines each year, one every six months.
Effective Date: October 1, 2027
Details: Vehicles equipped with On-Board Diagnostic (OBD) systems will be required to submit emissions tests four times per year.
California-Registered Vehicles:
Compliance deadlines are linked to the vehicle’s DMV registration renewal date. A passing emissions test must be submitted within the 90-day window prior to the compliance deadline.
Out-of-State Vehicles:
Testing Windows: Passing test results may be submitted up to 90 days before a compliance deadline. Testing Requirements: Vehicles with OBD systems (typically 2013 and newer diesel engines) require an OBD data scan. Non-OBD vehicles require a smoke opacity test and a visual inspection of emissions control equipment.
Enforcement: Non-compliance can result in fines, DMV registration holds, or other enforcement actions.
For the most current information and specific compliance deadlines for your vehicles, it’s advisable to consult the CARB Clean Truck Check official page or access your account in the CTC-VIS portal.
Each vehicle will have a compliance test deadline in 2025. Owners must submit passing tests within 90 days before these deadlines. The dates for compliance deadlines vary for vehicles registered within and outside of the state of California.
Compliance deadlines for California registered vehicles are based on their DMV registration expiration dates and every six months thereafter. This applies to any vehicles historically registered with CA DMV even if they are now registered outside of California. Compliance Deadlines may be found in the vehicle’s CTC-VIS account, and these due dates are what are used to calculate your compliance status.
Vehicles are required to ensure that they have paid their annual compliance fee and have no outstanding enforcement violations as part of their compliance demonstration.
The following vehicles’ compliance deadlinesare based on the last number of the vehicle’s Vehicle Identification Number (VIN).
Please refer to Table II below. These vehicles will have reoccurring compliance deadlines every six months.
Compliance Deadlines may be found in the vehicle’s CTC-VIS account, and these due dates are what are used to calculate your compliance status.
Bolded months indicate the month the compliance fee will be due.
As with CA registered vehicles, non-CA registered vehicles are required to ensure that they have paid their annual compliance fee and have no outstanding enforcement violations as part of their compliance demonstration.
While penalties can vary, most violations can result in a citation or a blocked vehicle DMV registration. A fine can be costly, but a blocked registration affects operations and can be difficult to work around. If you receive a citation, you will need to pay the designated civil penalty and provide proof of correction before the citation can be cleared.
Some potential violations of the Clean Truck Check and PSIP programs include:
These penalties take some time to clear and process and can put your vehicle out of commission for a while. The best way to avoid them is to stay proactive. Keep a close eye on your compliance deadlines and take advantage of your OBD systems wherever possible.
As the CARB Clean Truck Check program phases in, all affected vehicle owners—including independent operators and non-fleet owners—must take steps now to prepare. Planning ahead will make the transition smoother and help you stay compliant without last-minute stress or risk of penalties.
Here’s how to get started:
The program applies to diesel, alternative fuel, and other non-gasoline trucks and buses with a Gross Vehicle Weight Rating (GVWR) over 14,000 pounds.
Some vehicles may be exempt—be sure to review the exemption list provided in this guide.
Subscribe to Clean Truck Check notifications on CARB’s website to receive timely updates about:
When the reporting database becomes available
Upcoming compliance deadlines
Changes to program requirements
Staying informed is key to maintaining compliance.
Once the CARB system opens:
Be ready to report vehicle and fleet details, including DMV registration info
Have your information organized for quick submission
Set aside $30 per vehicle for the annual compliance fee
Once submitted, you’ll receive a Certificate of Compliance for each vehicle.
To ensure your vehicles pass emissions testing:
Verify that emissions systems are in proper working order
Create a testing and maintenance plan
If using in-house staff for testing, ensure they are certified Clean Truck Check testers
Consider installing On-Board Diagnostic (OBD) systems, if not already equipped
Establish a routine to track deadlines and keep your fleet compliant year-round
PEAQS is a roadside emissions screening tool used at locations like weigh stations and border crossings. As vehicles drive past, PEAQS captures real-time snapshots of tailpipe emissions. While it doesn’t replace formal testing, it serves as an initial filter to detect high-emitting vehicles operating on California roads.
Note: If a vehicle is flagged by PEAQS as a high emitter, the owner will receive a Notice to Submit to Testing (NST). The owner must then submit a passing compliance test within 30 days.
OBD systems are required for 2013 and newer diesel engines and 2018 and newer alternative fuel engines. They collect emissions data directly from the vehicle’s electronic system and share it with technicians via a CARB-certified OBD reader.
Testing must be conducted by credentialed Clean Truck Check testers using approved devices.
Testers upload the results directly to CARB’s compliance database.
Some telematics service providers are also approved to collect and transmit OBD data.
Anyone, regardless of location, can become an authorized tester by completing CARB’s free online training and passing the official exam.
Vehicles without OBD systems—generally model year 2012 and older—must undergo:
A Smoke Opacity Test using an SAE J1667-compatible meter.
A visual and functional inspection of all emissions control equipment.
Only credentialed testers can perform these inspections, and all results must be reported to CARB.
PSIP has long been used to monitor in-state fleets. While similar in method to smoke opacity testing, PSIP is being phased out as the Clean Truck Check program becomes fully operational. It remains in effect during the early rollout phase of HD I/M but will not be required once full implementation is complete.
CARB separates vehicles by engine model year for ongoing testing:
Testing Frequency:
Twice per year initially
Quarterly (4x/year) starting October 2027
Exceptions:
California motorhomes and on-road agricultural vehicles only require annual testing.
Testing Frequency:
Smoke opacity test + visual inspection every 6 months
Diesel engines are subject to both tests
California motorhomes and ag vehicles require annual testing only
To be fully compliant with the Clean Truck Check program, vehicle owners must ensure:
✅ No outstanding enforcement actions
✅ No unresolved emissions-related recalls
✅ Accurate owner and vehicle info is reported to CARB
✅ Annual $30 compliance fee is paid
✅ A passing emissions test has been submitted on time
Once these criteria are met, your vehicle is considered compliant and cleared to operate on California roads.
Many people in the trucking industry are used to handling problems on their own. However, when it comes to CARB regulations, there’s nothing wrong with asking for a hand. Our friendly staff will help you navigate the system to keep your vehicles active and on the road. We take the headaches out of CARB compliance!
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