3 Ways to Test Your Truck for the Clean Truck Check
Published
California's Clean Truck Check applies to almost every diesel and alternative-fuel vehicle over 14,000 lb GVWR that operates in the state. If you're reading this, odds are good at least one truck under your control falls into that bucket. There are three ways to satisfy the testing requirement, and which one fits depends on your fleet, your local options, and how much your truck's downtime actually costs you.
This post is a short tour. For the full side-by-side on costs, downtime, and coverage, see the longer testing options comparison page.
1. In-shop testing
The traditional approach. Drive the truck to a CARB-credentialed shop, the credentialed tester runs the CTC test, and the shop submits the result to CTC-VIS. The test itself takes about 15-30 minutes, and the certificate typically appears in your CTC-VIS dashboard within a day or two.
How the costs stack up
Most CARB-credentialed shops in California quote between $90 and $300 per test in mid-2026. That's only the test fee — the truck is also off the road for 1-3 hours including drive time and shop wait, which is its own cost. At a conservative $80/hour revenue-loss figure, that's another $80-$240 of opportunity cost per test, on top of the fee.
And you pay per attempt, not per pass: a failed or "Not Ready" result still costs you the test, and a retest after the issue is fixed is another charge. There's no reliable way to know in advance whether a given truck will pass, so the per-test price is really a per-attempt price.
Finding a shop
CTC Directory maintains the searchable list of every CARB-credentialed tester in the program. To find an in-shop tester near you, use the search page or browse by state. California fleets start with the California state hub.
2. Mobile testing
A credentialed mobile tester drives to your yard with the test equipment. The trucks stay where they are; the tester moves. Each truck cycles through the test in about 15-25 minutes — a 10-truck batch visit typically wraps in 3-4 hours. No drive-time per truck, no shop scheduling, no waiting for an open bay.
How the costs stack up
Mobile rates run higher than in-shop — typically $120-$350 per test — because the provider carries equipment and tester time to your location. What you save is downtime: zero per-truck drive time, batched scheduling, near-zero waiting overhead. For fleets that can fill a mobile visit (5+ trucks at one stop), the all-in cost-per-test comes out comparable to in-shop, and the time savings are real.
As with in-shop, you pay per attempt — a failed or "Not Ready" result and any retest are each their own charge, and there's no way to be sure a truck will pass before the tester runs it.
Finding a mobile tester
For Southern California specifically, we operate Clean Truck Check Pro (CTCP) — that's our disclosed bias. Coverage spans LA Basin, Inland Empire, and San Diego. For other regions, mobile providers exist but are scattered; we surface the mobile-capable testers across the directory's state and city pages.
3. Clean Truck Check device remote testing
A CARB-approved device plugged into the truck's OBD port runs the Clean Truck Check test on a schedule set by the truck's requirements, over cellular networks. The device doesn't pass or fail the test itself — it transmits the data to CARB, and CARB issues the result in your CTC-VIS account. No shop visit. No mobile visit. No driver action. No scheduling. Instead of a per-test fee, you pay one flat per-vehicle subscription that covers every test, including retests.
How the costs stack up
Clean Truck Check device pricing is a flat per-vehicle subscription — no per-test fees and no per-retest fees, with all tests and retests included. The critical difference is that the subscription cost does not change when the cadence goes from biannual to quarterly in 2028, so the per-test math gets better as cadence increases.
Finding an Clean Truck Check device subscription
Our operator team runs Smart CTC, which is the Clean Truck Check device subscription product in the family. Coverage extends across the US, Canada, and Mexico. That's the bias to be aware of: this directory is operated by the same team. Other Clean Truck Check device providers exist; the CARB credential is what you care about technically. Brand is secondary.
The 2028 wrinkle
One thing to know if you're running this calculation today: CARB's testing cadence shifts from twice a year to four times a year, applied to compliance deadlines in 2028 and beyond. Because the 90-day pre-deadline testing window opens before the deadline date, the new cadence starts executing in Q4 2027 for fleets with early-2028 deadlines.
For in-shop and mobile, that doubles the annual test count (and the annual fee total). For Clean Truck Check device, the subscription cost stays flat — the device just submits twice as many tests against twice as many windows. We have a dedicated page going deep on this: CARB Clean Truck Check 2027 Testing Changes.
Next steps
If you want a longer treatment of the comparison, start with the cornerstone. If you're looking to compliance-check your current fleet, the directory and the CTCP/Smart CTC pages are the operational starting points.
Need to know when your next test is due?
The free calculator handles the math for you — across multiple vehicles, including the 2028 OBD quarterly transition.
This post is published by the team behind CTC Directory, Smart CTC (Clean Truck Check device testing), and Clean Truck Check Pro (mobile testing). We have a commercial interest in two of the three options described. We've made our best effort to present every option fairly.