Truck smog check in LA County: Carson, Compton, Pomona

Short answer: Truck emissions testing in Los Angeles County is done under CARB's Clean Truck Check program, and Diesel Dynamix brings the test to you. We drive to yards, terminals, jobsites and homes in Carson, Compton, Pomona, Santa Fe Springs, City of Industry and the rest of the county, so your truck does not have to leave the lot. The test your truck needs depends on its engine model year.

What is a diesel truck smog check in Los Angeles?

A diesel truck smog check in Los Angeles is the CARB Clean Truck Check, not the BAR smog check used for cars. It applies to most diesel and alternative-fuel vehicles over 14,000 lb GVWR that operate in California, including trucks registered in other states and other countries.

Drivers call it a smog check because it does the same job: it shows the truck's emissions system is working. But the rules, the reporting system and the testers are different. Our post on Clean Truck Check vs smog check explains the difference in more detail.

The program has three parts for every covered truck:

1. Report the vehicle in CARB's CTC-VIS system.
2. Pay CARB's annual compliance fee for it, in CTC-VIS.
3. Pass the required test by the deadline shown in CTC-VIS.

Which heavy duty emissions test does my LA County truck need?

Heavy duty emissions testing in Los Angeles County follows the same rules as the rest of the state. Your engine model year and fuel type decide the test:

• 2013 and newer diesel: a CARB-verified OBD test. The tester plugs into the truck's diagnostic port.
• 2012 and older diesel without OBD: a smoke opacity test plus a visual inspection.
• 2018 and newer alternative fuel: a CARB-verified OBD test.
• 2017 and older alternative fuel without OBD: a visual inspection.

Most covered vehicles currently test twice a year. Under CARB's original rule, OBD-equipped 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. Your own deadlines are always in CTC-VIS.

Where do you do truck emissions testing in Los Angeles County?

We do mobile truck smog check visits across Los Angeles County. Below are the truck-heavy areas we drive to most. If your city is not named, ask anyway. See the Los Angeles service page for the full picture.

Truck emissions test in Carson, CA

Carson sits between the 405 and the 110, close to the Ports of Los Angeles and Long Beach. It is full of container yards, chassis lots and drayage operations. We test drayage tractors and yard trucks right where they park, which saves a trip through port traffic. Trucks that work the harbor can also use our Long Beach page and the Port of Long Beach page.

Truck smog check in Compton

Compton has a mix of trucking yards, owner-operators who park at home and small fleets along the 91 and 710 corridors. Owner-operators can book a single truck. We come to the yard or the home where the truck is parked.

Truck smog check in Santa Fe Springs

Santa Fe Springs is one of the busiest industrial areas in the southeast part of the county. Manufacturers, distributors and fuel haulers run box trucks, tankers and tractors out of the same lot. We can test several trucks in one visit and keep a record for each VIN.

Diesel smoke test in City of Industry

City of Industry is a long warehouse and distribution corridor along the 60. Many fleets there still run older trucks next to newer ones. A diesel smoke test in City of Industry is for 2012 and older diesel engines without OBD, while newer trucks in the same yard get the OBD test. We bring the equipment for both.

Truck smog check in Pomona

Pomona sits at the east edge of the county, where the 10, 57 and 71 meet. Its yards serve both Los Angeles County and the Inland Empire. If your trucks run between the two, our Inland Empire page covers the other side of the county line.

Other LA County truck areas

We also drive to Vernon, Commerce, Wilmington, Gardena, Rancho Dominguez, Paramount, El Monte, Irwindale, Sun Valley, Pacoima and the San Fernando Valley. Jobsites anywhere in the county are fine too.

Why is mobile testing useful in Los Angeles?

Mobile testing is useful in Los Angeles because a truck that leaves the yard to get tested is a truck that is not working. Traffic on the 710, the 605 and the 60 can turn a short drive into half a day.

With a mobile truck smog check in Los Angeles, the tester comes to the truck:

• No driving to a test site.
• Several trucks can be tested in one stop.
• Early-morning visits are available, before trucks head out.
• You get results in plain English and the next due date for each truck.

What should I have ready before the tester arrives?

Have the truck reported in CTC-VIS and CARB's compliance fee paid before the test. Then keep these ready:

• Keys and cab access, and a contact on site or by phone.
• The VIN and unit number for each truck, so results match the right vehicle.
• A truck with no check engine light on. A lit MIL fails the OBD test. Our guide to readiness monitors and the check engine light explains why.
• For older trucks, a warm engine. The smoke opacity test works best on a truck at normal operating temperature.

What if my truck fails in Los Angeles?

If your truck fails, it needs repair and then a retest. Common causes are a check engine light, readiness monitors that are not set, DPF or other emissions faults, and tampered or deleted equipment.

We do not do repairs. We test and explain the result so you know what to tell your shop. Deleted or tampered systems fail and are illegal, so we do not help with deletes. See what to do after a failed Clean Truck Check.

Staying current matters. California-registered trucks that fall out of compliance can get a DMV registration hold, and CARB can issue citations and penalties.

How Diesel Dynamix helps

Diesel Dynamix is an independent mobile testing service, not CARB or a government agency. In Los Angeles County we:

• Test at your yard, terminal, jobsite, port or home.
• Run the OBD test, the smoke opacity test and the visual inspection.
• Help with CTC-VIS questions and explain results in plain English.
• Give each truck's next due date and send reminders.
• Set up recurring visits for fleets, with records per truck and VIN.

Pricing depends on how many trucks you have, the test type and the location, with per-truck pricing for fleets. Call or text (858) 342-8328, message us on WhatsApp, or book online. For the county overview, see Los Angeles and Long Beach, and for fleets see fleet testing.