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California’s Clean Truck Check program isn’t going anywhere. If you’re running a 2013 or newer diesel truck over 14,000 pounds GVWR, you’re required to test your emissions control systems using OBD testing equipment—and those results go straight to CARB.
When you fall out of compliance, the DMV puts a hold on your registration. Your truck sits. You’re not making money, and every day costs you more than just the testing fee.
We handle CARB emissions testing for heavy-duty vehicles in Monrovia and throughout Los Angeles County. We’re CARB-credentialed testers who know exactly what your truck needs to pass, and we report results directly to the state. Most holds clear within 24 to 48 hours once your test is submitted.
You don’t need to figure out the regulations yourself. You need your truck back in service.
We’ve been serving Monrovia and the San Gabriel Valley with emissions testing and smog services for years. We’re not just a smog shop that dabbles in heavy-duty—we’re certified by CARB to perform Clean Truck Check testing on OBD-equipped diesel trucks.
Monrovia sits right in the heart of Los Angeles County, where air quality regulations are some of the strictest in the country. That means enforcement is real, and the testing requirements aren’t suggestions. We see fleet operators, owner-operators, and small trucking companies every week dealing with the same thing: surprise DMV holds, roadside inspection notices, and confusion about what’s actually required.
We stay current on CARB’s HD I/M regulations because they change. What applied last year might not apply now, and starting in 2027, testing frequency increases to quarterly for OBD-equipped trucks. You need someone local who knows the rules and can get your paperwork filed correctly.
First, we confirm your truck qualifies. This service only applies to diesel trucks that are model year 2013 or newer with a GVWR over 14,000 pounds. If your truck is older or lighter, it’s not subject to Clean Truck Check testing—but it may need other compliance work.
Once we verify eligibility, we connect our CARB-certified OBD testing device to your truck’s diagnostic port. The scan pulls data directly from your engine’s emissions control system. We’re checking for fault codes, system readiness, and whether your diesel particulate filter and other emissions equipment are functioning as designed.
The test itself takes less than an hour in most cases. If your truck passes, we submit the results electronically to CARB that same day. CARB processes the data and notifies the DMV, which typically lifts the registration hold within one to two business days.
If your truck doesn’t pass, we’ll tell you what’s flagged and what needs repair. You’ll need to fix the issue before retesting, but at least you’ll know exactly what’s wrong instead of guessing. Once repairs are done, you come back, we retest, and submit clean results.
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You’re paying for a CARB-credentialed tester to run a state-mandated emissions scan on your heavy-duty truck using certified equipment. That’s the baseline. But what you’re really getting is someone who knows how to navigate the system so your truck gets back to work.
In Monrovia and across LA County, trucking is a major part of the local economy. Freight moves through here constantly, and downtime is expensive. If your truck is sitting because of a compliance issue, you’re losing $300 to $900 a day depending on the work you’re missing. That’s why speed matters.
We also handle Notice to Submit to Testing letters. If you got pulled over at a CARB roadside inspection or received a letter in the mail saying your truck needs testing within 30 days, we can perform that test and file the results before the deadline. Missing that deadline means fines—up to $1,000 per day per vehicle in some cases.
This isn’t just about avoiding penalties. It’s about keeping your operation running without surprises. California’s regulations aren’t getting looser, and CARB is adding more monitoring stations and increasing testing frequency. Staying compliant now means fewer problems later.
If your truck is model year 2013 or newer and has a GVWR over 14,000 pounds, it needs a Clean Truck Check test, not a traditional smog check. This is OBD-based emissions testing that scans your engine’s diagnostic system using CARB-certified equipment.
Older trucks or lighter vehicles may fall under different testing requirements, or none at all depending on the year and weight class. If you’re not sure, bring in your registration or VIN and we’ll tell you exactly what applies.
The confusion usually comes from the fact that California has multiple emissions programs depending on vehicle type and age. Clean Truck Check is specifically for newer heavy-duty diesel trucks, and the results get reported directly to CARB, not just the DMV.
Once we submit your passing test results to CARB, the hold typically clears within 24 to 48 hours. CARB processes the data and notifies the DMV electronically, and the DMV updates your registration status.
In some cases it happens faster—same day if everything processes smoothly. In rare cases it can take up to three business days if there’s a backlog or a data mismatch that needs manual review.
You can check your status online through the DMV’s website or by calling their registration unit. Once the hold is lifted, you can renew your registration and get back on the road. We don’t control the DMV’s processing time, but we make sure the paperwork is filed correctly so there’s no delay on our end.
If your truck fails, we’ll give you a detailed report showing which emissions system triggered the failure. Common issues include fault codes related to the diesel particulate filter, NOx sensors, or exhaust gas recirculation systems.
You’ll need to get the problem repaired before retesting. We can point you toward what needs fixing, but we don’t perform the actual engine or emissions repairs here. Once the repair is done, bring the truck back and we’ll retest it.
The good news is that OBD testing tells you exactly what’s wrong instead of making you guess. You’re not throwing parts at the problem or hoping a mechanic figures it out. The diagnostic data is specific, and a qualified diesel mechanic will know how to address it. After repairs, most trucks pass on the second test.
Right now, most heavy-duty trucks with 2013 or newer engines are required to test twice a year under California’s Clean Truck Check program. That’s the current standard as of 2025.
Starting in 2027, CARB is increasing the frequency to four times a year—quarterly testing—for OBD-equipped vehicles. That’s not in effect yet, but it’s coming, and it’s worth planning for if you’re managing a fleet or running multiple trucks.
The testing schedule is tied to your vehicle’s compliance status and registration cycle. If you get a Notice to Submit to Testing from CARB, you’re required to test within 30 days regardless of when you last tested. Roadside inspections and enforcement actions can also trigger mandatory testing outside the regular schedule.
We primarily operate out of our Monrovia location, so you’ll need to bring the truck in for testing. The process is fast—usually under an hour—so it’s not a major disruption to your day.
Some testing providers offer mobile service where they come to your yard with portable equipment. We don’t currently offer that, but the advantage of coming to us is that we have a full facility, backup equipment if needed, and the ability to handle any issues that come up during the test.
If you’re managing a fleet and need to test multiple trucks, call ahead and we can schedule a block of time to get them all done efficiently. That way you’re not making multiple trips or waiting around between tests.
Bring your vehicle registration or VIN so we can verify the truck’s information and confirm it’s subject to Clean Truck Check testing. If you received a Notice to Submit to Testing letter from CARB or the DMV, bring that too.
You don’t need to bring maintenance records or proof of repairs unless your truck previously failed a test and you’re coming back for a retest. In that case, it’s helpful to have documentation showing what was fixed, but it’s not required for us to run the test.
Make sure your truck’s check engine light isn’t on when you arrive. If it is, the truck will fail automatically because the OBD system is reporting an active fault. Get that checked and cleared before testing, or you’ll be making two trips.
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