California's Clean Truck Check program mandates semi-annual emissions testing for trucks over 14,000 lbs. Fleet owners in LA and Riverside counties face strict deadlines, quarterly testing by 2027, and steep penalties for non-compliance.
If you operate commercial trucks in Los Angeles County or Riverside County, the Clean Truck Check program directly impacts your ability to keep vehicles on the road. This isn’t a voluntary program—it’s mandatory CARB compliance with real consequences for missing deadlines.
This guide breaks down exactly what the Clean Truck Check CARB program requires, how quarterly testing works, when your compliance deadlines fall based on registration or VIN, and what enforcement looks like on the ground. Whether you’re managing a large fleet or running as an owner-operator, understanding these Clean Truck Check requirements protects your business from registration holds, daily fines, and lost contracts.
The Clean Truck Check is California’s emissions testing and compliance program for heavy-duty vehicles. Think of it as a smog check for commercial trucks, but with teeth. It applies to nearly all diesel and alternative fuel vehicles with a gross vehicle weight rating over 14,000 pounds that operate on California public roads and highways.
CARB approved the program in December 2021, and it’s been rolling out in phases since January 2023. It replaces the old Periodic Smoke Inspection Program, but with a much wider reach. Where the previous program exempted most independent owner-operators, the Clean Truck Check CARB program covers everyone—large fleet operators, single-truck owner-operators, out-of-state carriers, government vehicles, and even diesel motorhomes.
The goal is straightforward: ensure emissions control systems on heavy-duty trucks work properly throughout the vehicle’s life. Heavy-duty trucks make up only 3% of vehicles on California roads but produce more than 50% of nitrogen oxide emissions and fine particulate matter from all vehicles. In areas like Los Angeles County and Riverside County, where air quality already fails federal standards, that pollution has real health consequences.
If your truck weighs more than 14,000 pounds GVWR and runs on diesel or alternative fuel, you’re subject to Clean Truck Check requirements when it operates in California. That’s the baseline, and there’s no wiggle room.
This includes semi-trucks, box trucks, dump trucks, tow trucks, refuse haulers, commercial buses, motorcoaches, and diesel motorhomes registered in California. It doesn’t matter if you own one truck or 500. It doesn’t matter if your business is based in downtown Los Angeles, out in Riverside County’s logistics corridors along the I-10 and I-15, or halfway across the country. If your vehicle operates on California public roads or highways, it needs to be registered in the CTC-VIS system and tested on schedule.
Out-of-state carriers often assume they’re exempt because their trucks carry Nevada, Arizona, or Texas plates. That assumption is wrong, and it’s costing operators money. California enforces Clean Truck Check on any qualifying vehicle operating within the state, regardless of where it’s registered. That means if you’re hauling freight into the Ports of Los Angeles or Long Beach, delivering to warehouses in the Inland Empire, or just driving through California on your way to another state, your trucks still need to be compliant. CARB conducts field inspections at border crossings, weigh stations, and outside major freight facilities specifically to catch out-of-state trucks that haven’t registered.
The program also applies to vehicles that don’t typically register with the DMV, like certain government and military vehicles. Even if your plates say “exempt,” you’re not exempt from Clean Truck Check. Hybrid trucks fall under the requirement too, as long as they meet the weight threshold.
There are a few exemptions. Zero-emission vehicles like battery-electric and hydrogen fuel cell trucks don’t need emissions testing because they produce no tailpipe emissions. Some emergency vehicles, historical vehicles, and off-road-only equipment are also excluded. But if you’re running a standard diesel commercial truck, don’t assume you’re off the hook. Check your status in the CTC-VIS system to be certain.
One more thing fleet owners need to understand: freight brokers, shippers, and facilities like ports and railyards are now required to verify Clean Truck Check compliance before they contract with carriers. If your fleet isn’t compliant, you could lose access to work, not just face fines. That makes this more than a regulatory checkbox—it’s a business survival issue. In logistics-heavy areas like Riverside County, where competition for contracts is fierce, non-compliance can shut you out of opportunities before you even get a chance to bid.
Your Clean Truck Check deadline depends on where your vehicle is registered. California uses two different schedules, and understanding which one applies to your trucks is critical to avoiding penalties.
For trucks registered in California, your compliance deadline is tied directly to your DMV registration expiration date. If your registration expires in January, your first Clean Truck Check test is due in January. Six months later, you’ll have another deadline in July. This pattern repeats every six months for the life of the vehicle. The system is designed to align with your existing registration cycle, so you’re handling both compliance requirements at the same time. Miss your Clean Truck Check deadline, and the DMV will place a registration hold on your vehicle—you won’t be able to renew until you’re back in compliance.
For out-of-state registered vehicles and California vehicles with exempt plates, deadlines are based on the last digit of your Vehicle Identification Number. CARB has assigned specific months to each VIN ending. For example, if your VIN ends in 0, your deadlines fall in January and July. If it ends in 5, you’re looking at March and September. If it ends in 9, your deadlines are in June and December. This system spreads testing demand throughout the year and prevents bottlenecks at testing facilities.
You can find your exact Clean Truck Check deadlines by logging into your CTC-VIS account. The system tracks every vehicle you’ve registered and displays upcoming due dates in the Testing Details tab. CARB also sends monthly email summaries listing vehicles with deadlines in the next 90 days, which gives you a planning window if you’re managing multiple trucks across different schedules.
Here’s something that trips people up, but it’s actually one of the most useful features of the program: you can submit a passing test up to 90 days before your deadline. That’s not just a courtesy—it’s a strategic advantage. If your deadline is February 1, 2026, you can test as early as November 3, 2025, and still be covered. This matters because if your truck fails the test, you have time to make repairs and retest before the deadline hits. If you wait until the last minute and fail, you’re racing the clock to avoid penalties while your truck sits idle.
Semi-annual testing is the current standard for most commercial vehicles. That means twice a year, every year, for as long as you operate in California. Agricultural vehicles and California-registered motorhomes used for recreation get annual testing instead of semi-annual. But here’s what’s coming: starting October 2027, vehicles equipped with on-board diagnostics systems will move to quarterly testing. That’s four times a year. If your truck has a 2013 or newer diesel engine, you’ll be in that group. For fleet operators managing dozens or hundreds of trucks, that’s a significant increase in compliance workload. Plan for it now.
Missing a Clean Truck Check deadline isn’t just an inconvenience or a slap on the wrist. Non-compliance triggers DMV registration holds, which means you can’t renew your registration until you’re back in compliance. Your truck is effectively grounded—can’t legally operate on California roads. On top of that, you’re exposed to fines that can reach $10,000 per vehicle per day for non-compliance. That’s not a typo. Ten thousand dollars. Per vehicle. Per day. For a small fleet of five trucks, that’s $50,000 in potential daily fines if you’re out of compliance.
Enforcement is active and aggressive. CARB has been using roadside emissions monitoring devices since January 2023 to screen trucks in real time. These sensors are deployed throughout California, with heavy concentration in the South Coast Air Basin (which includes Los Angeles County) and the San Joaquin Valley. If your truck triggers one of these sensors, you’ll receive a Notice to Submit to Testing in the mail. You’ll have 30 days from receipt to submit a passing test. Ignore it, and the penalties escalate quickly—enforcement violations, registration holds, and potential impoundment of your vehicle.
Clean Truck Check testing requirements depend on your truck’s engine type and model year. CARB splits vehicles into two categories: those with on-board diagnostics systems and those without. The testing method is completely different for each, and using the wrong method will result in a failed test that doesn’t count toward your compliance deadline.
If your truck has a 2013 or newer diesel engine, or a 2018 or newer alternative fuel engine, it’s equipped with OBD. Testing involves scanning the engine’s OBD data using a CARB-certified testing device. The scan checks for active fault codes, confirms that emissions control systems are functioning properly, and verifies that readiness monitors have completed their self-checks. It’s a digital process that takes about 15-20 minutes if the truck passes. The tester plugs the device into your diagnostic port, pulls the data, and uploads the results directly to the CTC-VIS system.
For older trucks—2012 and earlier diesel engines—testing requires a smoke opacity test and a visual inspection of emissions control equipment. The smoke test measures how much particulate matter is coming out of the exhaust under load. The visual inspection checks that components like diesel particulate filters, EGR systems, selective catalytic reduction units, and diesel oxidation catalysts are present, intact, and haven’t been tampered with or removed. If you’re running a 2017 or older alternative fuel engine, you only need the visual inspection, not the smoke test.
Before you can test, you need to register your vehicles in the Clean Truck Check Vehicle Inspection System, known as CTC-VIS. This is a separate system from TRUCRS, which handles other CARB programs like the Truck and Bus Regulation. Even if you’re already registered in TRUCRS for other compliance requirements, you need to create a new account in CTC-VIS specifically for Clean Truck Check. The systems don’t talk to each other, and CARB won’t transfer your data automatically.
Registration requires basic information: your business name or personal details if you’re an owner-operator, vehicle identification numbers for each truck, engine model years, fuel types, and current registration information. If you operate multiple trucks, you can register them all under one company account. The system will assign compliance deadlines to each vehicle based on its registration status or VIN, and you’ll be able to track everything in one dashboard.
Once your vehicles are registered, you need to pay the annual compliance fee. As of 2026, the fee is $32.13 per vehicle. This fee is adjusted every year based on California’s Consumer Price Index, so expect it to increase slightly each January. Payment must be made through CTC-VIS using a credit card, debit card, or e-check. Paper checks aren’t accepted. Payments made through other CARB portals won’t count toward your Clean Truck Check compliance—it has to go through CTC-VIS.
The fee is due at your compliance deadline, which means it’s tied to your testing schedule. If your first test is due in March, your fee is due in March. You can’t skip the fee and just submit a test—both are required to maintain compliance. If you miss the fee deadline, your vehicle will be flagged as non-compliant in the system, which can trigger registration holds and open you up to enforcement action even if you’ve completed the test.
Here’s something fleet operators managing large numbers of vehicles should know: if you’re running 10, 50, or 200 trucks, CTC-VIS allows you to download a compliance certificate for your entire fleet once all vehicles are compliant. This is called an Affirmation of Fleetwide Compliance, and it’s incredibly useful when dealing with freight brokers or shippers who need to verify your compliance status before they’ll contract with you. Instead of pulling individual certificates for every single truck in your fleet, you can provide one document that covers your whole operation. That saves time and makes you more competitive when bidding for contracts in fast-moving markets like Los Angeles County and Riverside County.
Registration and fee payment aren’t one-time tasks. If you add a new vehicle to your fleet, you’re required to report it in CTC-VIS within 30 days of acquisition and pay the compliance fee for that vehicle. If you sell a vehicle or take one out of service, you need to update your account within 30 days as well. Keeping your account current prevents issues down the line, especially if CARB runs an audit or your trucks are stopped for inspection at a port, weigh station, or border crossing.
Clean Truck Check testing must be performed by a CARB credentialed tester. That means the person conducting your test has completed CARB’s official online training course, passed the exam with a score of at least 80%, and holds a current, valid certificate. Credentials are valid for two years, so testers need to renew regularly to stay authorized. You can’t just have anyone with a scan tool or smoke meter test your truck—it has to be someone CARB has specifically credentialed and authorized to submit results to the CTC-VIS system.
If your truck has OBD, the tester connects a CARB-certified testing device to the vehicle’s diagnostic port. The device pulls data from the engine’s computer, checking for active or pending fault codes and confirming that emissions-related monitors are in a “ready” state. If the truck has a check engine light on, or if the monitors haven’t completed their self-checks (which can happen after a recent repair or battery disconnect), the test will come back as “Not Ready” and won’t count as a passing result. The tester uploads the results directly to CTC-VIS in real time, and you’ll see them appear in your account within a few hours.
For non-OBD vehicles, the process is more hands-on and takes longer. The smoke opacity test involves bringing the engine up to operating temperature, then running it through a series of snap acceleration cycles while measuring the density of exhaust smoke using a certified smoke meter. The visual inspection requires the tester to physically access emissions control components under the hood and underneath the vehicle, documenting their condition on a Vehicle Emissions Control Equipment Inspection Form. Both the smoke test results and the completed inspection form are submitted to CARB through the tester’s CTC-VIS account.
If your truck passes, you’re done. The passing result is recorded in CTC-VIS, your compliance status is updated, your next deadline is set for six months out (or three months if you’re in the quarterly testing group starting in 2027), and you’ll receive a certificate of compliance that you can download from your account. You don’t need to carry the certificate in your truck by law, but CARB recommends keeping a printed or digital copy accessible in case you’re stopped for inspection by the California Highway Patrol or CARB enforcement officers.
If your truck fails, the tester will provide details on what went wrong. Maybe there’s an active fault code that needs to be diagnosed and cleared. Maybe a sensor isn’t reading correctly. Maybe the smoke test showed excessive particulate emissions indicating a clogged diesel particulate filter or a failing turbocharger. Whatever the issue, you’ll need to address it and retest before your deadline. This is exactly why testing early—within that 90-day window before your deadline—is so important. It gives you time to fix problems, order parts if needed, and schedule a retest without missing your compliance deadline and triggering penalties.
One more scenario fleet owners need to be aware of: even if your truck passes its scheduled Clean Truck Check inspection, it can still be flagged as a high emitter between testing intervals. CARB has been deploying roadside emissions monitoring devices throughout California since January 2023. These sensors use remote sensing technology to measure emissions as trucks drive past at highway speeds. If your truck triggers one of these sensors and shows elevated emissions, you’ll receive a Notice to Submit to Testing in the mail. You’ll have 30 days from the date you receive the notice to submit a passing Clean Truck Check test to CARB. This is separate from your regular semi-annual or quarterly testing schedule, and it’s not optional. Failing to respond to a Notice to Submit to Testing can result in enforcement violations, fines, and registration holds.
