CARB Clean Truck Check: Your 2025 Guide to Compliance in California​

Keeping Your Trucks (and Wallet) in the Clear

The California Air Resources Board (CARB) is rolling out major enforcement for diesel vehicle emissions and if you’re a commercial operator, you’re on their radar. Whether you drive a box truck, sprinter van, or fleet van, the Clean Truck Check program (formerly HD I/M) is now mandatory.

At Darling Smog, we specialize in getting you compliant fast, with onsite and mobile testing options tailored to your workflow. No guesswork, no upsells, just straight-up compliance testing. Might be the easiest part of your day. 

Official program details here.

What Is the CARB Clean Truck Check Program?

CARB’s Clean Truck Check is a statewide emissions testing program for heavy-duty vehicles.  If your vehicle meets any of these criteria, it likely needs to be tested:

Diesel engine

GVWR over 14,000 lbs

Operating in California (even out-of-state plates!)

Common affected vehicles:

Box trucks, service vans, and light delivery vehicles (Class 3–6)

Work vans and utility vehicles used for business operations

Recreational vehicles (RVs) with current registration

Local package delivery trucks and route-based commercial vehicles

Not sure if your vehicle qualifies?
Submit your VIN or license plate through our form. 

What Happens During a CARB Test at Darling Smog?

Here’s how your appointment works with us:

Request your appointment online (onsite or mobile) we will confirm the details and send you a calendar link to select your appointment day/time

Bring your truck or we come to you

We test your vehicle with the appropriate method:

OBD II scan for newer trucks

Smoke opacity testing for older ones

Visual inspections for select fuel types

We submit results to CARB on your behalf

You’re done! Just wait for confirmation on your portal (usually 2 business days)
Need help using the CARB portal? Check out the CTC-VIS guide.

Want to know how to prep before arriving?
Check out our confirmation checklist.

What If I Got a CARB Non-Compliance Letter?

Take a deep breath, this just means it’s time to test.

The letter includes a deadline to test your truck and get it compliant. If you delay, you risk hefty fines and possible DMV registration blocks. But the good news? It’s fixable.

Bring your vehicle in before the deadline, and we’ll get you cleared.
You can also reference CARB’s official FAQ. 

Mobile Testing for Fleets & Field Operators

Too many trucks to bring in? Don’t want to coordinate getting your truck on-site? No worries. We’ll come to you.

Our mobile testing option is perfect for:

Commercial vehicles parked at approved business locations

Light- and medium-duty trucks (Class 3–6)

Delivery vans, service trucks, and fleet vehicles

Food trucks and trailers with valid business registration

All we need is safe access to each truck, a space to park and plug in, and some time to test each vehicle. Boom! Done.

Based in Glendora, we travel across SoCal to keep fleets clean and compliant.
Submit a mobile testing request.

CARB Testing Timeline & Paperwork

Most tests take under an hour per truck. 
We handle:

Official test submission

Confirmation of compliance

Readiness check (yes, monitors must be set)

We’ll send you a digital record after testing. You’ll also see it reflected on the CARB Clean Truck Check Portal (usually within 1–2 days).
Check the official timeline details on CARB’s site.

Why Choose Darling Smog?

We’re not a chain. We’re not a repair shop.
We’re emissions experts with a focus on trucks and diesel compliance and we’ve got that extra touch:

✅ Credentialized Clean Truck Testers and CARB-approved

✅ Fast scheduling and short wait times

✅ Friendly, woman and veteran-owned, small business

✅ Route 66 vibes, built for the long haul

✅ Field-tested mobile ops for high-volume fleets

If you want a quick in-and-out or full-fleet service with zero fluff, you’re in the right place.

 Let’s Get You Compliant

Skip the stress and stay ahead of CARB deadlines.
We’ll handle the testing! You focus on the road.