Who Can Perform a Clean Truck Check Test?

Short answer: a Clean Truck Check test must be done by a credentialed tester using CARB-verified equipment, and the result is submitted to CARB. That tester can work at a shop or come to you. Diesel Dynamix performs OBD and smoke opacity tests on site across Southern California. If you want to know the exact requirements for testers or devices, check CARB's Clean Truck Check rules.

Who can perform Clean Truck Check?

CARB decides who can submit a valid test. In general, the test is done by a tester who holds the credential CARB requires and uses equipment CARB has verified for the program. The result then goes into CARB's system, where it shows against the truck's VIN in CTC-VIS.

That means a regular repair shop scan, or a smog check at a station that only handles cars and light trucks, does not automatically count. Our Clean Truck Check vs smog check guide explains why.

Who can do a CARB OBD test?

The same rule applies. A CARB OBD test for Clean Truck Check is done with CARB-verified OBD equipment by a tester who meets CARB's requirements. The test reads the truck's onboard computer, checks for faults and readiness, and sends the data to CARB. See OBD testing for what the test covers.

Do I need Clean Truck Check?

Most diesel and alternative-fuel vehicles over 14,000 lb GVWR that operate in California need it. That includes out-of-state and international trucks, plus buses, refuse trucks, construction trucks, agricultural vehicles and motorhomes over 14,000 lb where they fall under the program. For edge cases, check CARB's rules for your vehicle.

Quick checks:

• Look at the GVWR on the door jamb label. Over 14,000 lb usually means the program applies.
• Diesel or alternative fuel? Both are covered.
• Does it operate in California? Registration state does not matter.

Read which vehicles need Clean Truck Check, does my pickup need Clean Truck Check and Clean Truck Check exemptions for more.

Which test will my truck get?

• 2013 and newer diesel: CARB-verified OBD test
• 2012 and older diesel without OBD: smoke opacity test plus visual inspection
• 2018 and newer alternative fuel: CARB-verified OBD test
• 2017 and older alternative fuel without OBD: visual inspection

Can I buy my own OBD device for Clean Truck Check?

CARB sets the rules on which devices are verified and who may use them to submit results. Before you buy any device marketed for Clean Truck Check, read CARB's current rules on its Clean Truck Check page so you know whether you could use it to submit tests and what else is required.

For many owners, especially those with one truck or a small fleet, it is simpler to have a tester come out. You avoid buying equipment, and you get someone who can explain the result.

Can I get a Clean Truck Check for one truck?

Yes. You do not need a fleet to book mobile testing. Owner-operators can have their truck tested at home, at a yard or at a jobsite. Our price depends on the number of trucks, the test type and the location. Fleets get per-truck pricing. See how much Clean Truck Check costs.

Can I get Clean Truck Check early?

Each truck has a testing window tied to its deadline, and that window is shown in CTC-VIS. Check your truck's window there before booking, so the test counts toward the deadline you are trying to meet. Our 2026-2027 deadlines guide and how often trucks need Clean Truck Check cover timing in more detail.

Most covered vehicles currently test twice a year. Under CARB's original rule, OBD vehicles move to four tests a year from October 1, 2027. A bill has proposed cutting testing to once a year, so this may change.

Who do I call for Clean Truck Check help?

It depends on the question:

• Fees, citations, holds and program rules: CARB, through its Clean Truck Check website and CTC-VIS.
• Registration renewal: the DMV, once CARB shows the truck as compliant.
• Booking a test, reading results, CTC-VIS questions: your tester. We help with CTC-VIS questions and explain results in plain English.

Diesel Dynamix is an independent testing service, not CARB or a government agency.

How to get your truck tested, step by step

1. Confirm the truck is covered using the checks above.
2. Register the truck in CTC-VIS and pay CARB's annual compliance fee. See the CTC-VIS registration guide.
3. Check the testing window for the truck in CTC-VIS.
4. Book a tester with CARB-verified equipment.
5. Get the result and next due date. If it fails, repair and retest.

How Diesel Dynamix helps

We perform OBD and smoke opacity tests at your yard, jobsite, terminal, port or home across Southern California, including Los Angeles, Long Beach, the Inland Empire, San Diego and El Centro.

• One truck or a full fleet. See fleet testing
• Plain-English results and the next due date
• Reminders and help with CTC-VIS questions
• Quotes by phone or WhatsApp

See how testing works and our Clean Truck Check FAQ, then book online or call or text (858) 342-8328.