- Deadline approaching? Call (858) 257-8576 Now
carb compliance isn't optional for commercial trucks in California. Here's what fleet owners and drivers need to know about testing, deadlines, and staying legal.
carb stands for the California Air Resources Board—the state agency responsible for regulating air quality and emissions. When people talk about carb compliance for trucks, they’re referring to a set of regulations that control how diesel and alternative fuel commercial vehicles operate in California.
The main goal is simple: reduce air pollution from heavy-duty trucks. Diesel exhaust is responsible for 70% of cancer risk from airborne toxics in California, and heavy-duty vehicles contribute more than half of all smog-causing pollution despite making up only 3% of vehicles on the road.
For you, carb compliance means your truck must meet specific emissions standards, undergo regular testing, and maintain properly functioning emissions control equipment. It doesn’t matter where your truck is registered. If it operates in California, it must comply.
carb regulations apply to nearly all diesel-powered trucks and buses with a gross vehicle weight rating over 14,000 pounds operating in California. This includes commercial vehicles, fleet trucks, motorcoaches, buses, hybrid vehicles, and even personal-use heavy-duty trucks.
It doesn’t matter if you’re based in California or just passing through. Out-of-state trucks, trucks registered in other countries, and vehicles with temporary plates all fall under the same requirements. If your wheels touch California roads, you’re subject to carb rules.
The regulations cover multiple areas. The Truck and Bus Regulation requires vehicles to have 2010 or newer model year engines. The Clean Truck Check program mandates periodic emissions testing and reporting. Both are actively enforced, and both carry serious penalties for non-compliance.
There are very few exemptions. The main one is the low-use exemption for vehicles operating less than 1,000 miles per year in California, but you have to apply for it and prove your mileage. Some agricultural vehicles and certain off-road equipment may qualify for modified requirements, but you’ll need to attest to that status and provide documentation.
Motor carriers, drivers, brokers, freight forwarders, and even California-based shippers and receivers all share responsibility for ensuring trucks meet carb standards. Everyone in the supply chain has skin in the game. Hire a non-compliant carrier, and you can be fined up to $10,000 per year for each non-compliant vehicle you used.
carb uses roadside emissions monitoring devices, automated license plate readers, and random inspections at weigh stations and border crossings to identify violators. They’re not just checking California-registered trucks. Enforcement is active at ports, railyards, and anywhere heavy-duty vehicles operate—including busy areas throughout Los Angeles County and Riverside County.
The bottom line: if you operate a truck over 14,000 pounds in California, assume you need to comply unless you’ve confirmed an exemption in writing from carb.
carb compliance breaks down into three main requirements: engine standards, emissions testing, and reporting.
First, the engine requirement. As of January 1, 2023, all diesel-powered vehicles operating in California with a GVWR over 14,000 pounds must have a 2010 or newer model year engine. This is part of the Truck and Bus Regulation that’s been phased in since 2008. Older engines don’t meet the particulate matter and nitrogen oxide emissions standards California requires. Your truck has a pre-2010 engine? It can’t legally operate in the state, and the DMV will deny your registration renewal.
Second, Clean Truck Check testing. This is California’s Heavy-Duty Inspection and Maintenance program, and it requires periodic emissions compliance testing. Most commercial trucks must undergo testing twice a year—semi-annually. Vehicles with 2013 or newer diesel engines (or 2018 or newer alternative fuel engines) will eventually need testing four times per year starting in October 2027.
Testing must be performed by a carb-credentialed tester using certified equipment. For OBD-equipped vehicles, that means scanning the engine’s onboard diagnostics data. For older non-OBD diesel engines, it means a smoke opacity test and visual inspection of emissions control equipment. Your credentialed tester submits the results directly to carb.
Third, registration and reporting. You must report your vehicles in the Clean Truck Check Vehicle Inspection System, known as CTC-VIS. This is the database where you register each truck, pay the annual $30 compliance fee per vehicle, and track your testing deadlines. Payments must be made online via debit, credit, or e-check—no paper checks accepted.
Compliance deadlines depend on where your truck is registered. California-registered vehicles follow their DMV registration expiration date. Out-of-state vehicles are assigned deadlines based on the last digit of the VIN. Miss your deadline, and you’ll face a DMV registration hold, meaning your truck can’t be renewed or legally operated.
carb also uses roadside emissions monitoring to screen for high-emitting trucks. If your vehicle gets flagged, you’ll receive a Notice to Submit to Testing. You then have 30 days to get your truck tested by a credentialed tester and submit passing results. Ignoring this notice leads to steep fines and registration blocks.
All of this applies whether you own one truck or manage a fleet of hundreds. The requirements don’t change based on the size of your operation.
The Clean Truck Check program is California’s emissions testing system for heavy-duty vehicles. It combines periodic testing requirements with roadside monitoring and enforcement to ensure trucks maintain properly functioning emissions control systems throughout their operational life.
The program started phasing in during January 2023 with roadside emissions monitoring. Compliance testing requirements became effective October 1, 2024, with the first testing deadlines beginning January 1, 2025. Haven’t registered your trucks in CTC-VIS or scheduled testing yet? You’re already behind.
Clean Truck Check aims to identify high-emitting vehicles early and require repairs before emissions systems fail completely. carb estimates the program will prevent 7,500 air-quality related deaths and 6,000 hospitalizations between 2023 and 2050, delivering $75 billion in health benefits.
Testing requirements depend on your engine type and model year. Newer engines with onboard diagnostics get scanned electronically. Older engines without OBD undergo physical smoke and visual inspections.
OBD-equipped vehicles—those with 2013 or newer diesel engines or 2018 or newer alternative fuel engines—must have their engine’s OBD data scanned using a carb-certified testing device. The scan checks for fault codes, monitors emissions control system performance, and verifies everything is operating within acceptable parameters. This test is quick, non-invasive, and submitted electronically to carb by your credentialed tester.
Non-OBD diesel vehicles with 2012 or older engines require a smoke opacity test and a visual inspection. The smoke test measures how much visible smoke your exhaust produces under load. The visual inspection confirms that emissions control equipment like diesel particulate filters, exhaust gas recirculation systems, and diesel oxidation catalysts are present, properly installed, and not tampered with.
Alternative fuel non-OBD vehicles with 2017 or older engines only need the visual inspection—they’re exempt from the smoke opacity requirement.
Testing can be done up to 90 days before your compliance deadline, giving you time to address any failures and make repairs. Truck fails the test? You’ll need to fix the issue and retest before the deadline. Missing your deadline triggers a registration hold.
You can’t perform the test yourself unless you’re a carb-credentialed tester. Credentialing requires completing carb’s free online training course and passing an exam with at least 80%. The certification must be renewed every two years. Most truck owners find it easier to hire a credentialed tester rather than handle testing in-house.
carb maintains a searchable database of credentialed testers available for hire. Some offer mobile testing services that come to your location, which can save downtime for fleet operators. Others operate fixed testing facilities. Either way, make sure your tester is current on their credentials and uses carb-certified testing equipment.
Once you pass, your tester submits the results to carb, and your compliance status updates in CTC-VIS. You’ll receive a certificate of compliance that should be kept in the vehicle. Drivers must be able to produce proof of compliance during roadside inspections.
Non-compliance with carb regulations leads to immediate, costly consequences. The California DMV automatically places registration holds on vehicles that don’t meet Clean Truck Check requirements. That means you can’t renew your registration, and operating the vehicle becomes illegal.
Get caught operating a non-compliant truck? Fines range from $1,000 to $75,000 per day depending on the violation’s severity. carb collected $21.5 million in penalties in 2022 alone, and enforcement has only increased since then. For a fleet, these fines can compound quickly—$10,000 per vehicle per day adds up fast when you have multiple trucks out of compliance.
Roadside inspections by carb enforcement and the California Highway Patrol can happen anywhere—at weigh stations, border crossings, outside ports and railyards, or random roadside locations. Truck gets stopped and you can’t provide proof of compliance? You’ll face citations and possible impoundment.
carb also uses roadside emissions monitoring devices to screen vehicles as they drive by. These sensors detect high emissions levels and flag trucks that may have malfunctioning emissions systems. If your truck gets flagged, you’ll receive a Notice to Submit to Testing in the mail.
Once you get that notice, the clock starts. You have 30 calendar days to have your truck tested by a credentialed tester and submit passing results to carb. Repairs needed? That 30-day window includes the time to fix the problem and retest. Ignoring the notice results in registration holds, fines, and potential enforcement action.
Even if your truck passed its last scheduled compliance test, it can still be flagged as a potential high emitter between testing intervals. Emissions systems can degrade over time, and carb’s monitoring is continuous.
For brokers and freight forwarders, hiring or dispatching non-compliant trucks carries its own penalties. You’re required to verify that any truck you assign to a California route is carb-compliant. Failure to do so can result in fines and legal action. The same goes for California-based shippers and receivers—you must confirm that carriers you hire meet carb requirements.
Non-compliance doesn’t just cost money. It damages your reputation, disrupts operations, and can block you from securing contracts. Many shippers and facilities now require proof of carb compliance before allowing trucks on-site.
The best approach is proactive compliance. Register your trucks in CTC-VIS early, pay your annual fees on time, schedule testing well before deadlines, and maintain your emissions systems properly. Catching problems during scheduled testing is far cheaper than dealing with a Notice to Submit to Testing or a roadside citation.
