CARB CTC Testing in Fremont: What to Expect
A practical guide to the Clean Truck Check test itself — how heavy-duty emissions testing works, how to prepare your truck, and what to do with the results.
If you're new to the program, start with our overview of CARB Clean Truck Check. This page focuses on the testing appointment: what happens, how to prepare, and what comes next.
How heavy-duty emissions testing works
CTC testing is performed by a CARB-credentialed tester and submitted to CARB. The method depends on the vehicle. For many newer trucks, testing is done through the truck's on-board diagnostics (OBD) system: the tester connects approved equipment to the diagnostic port and the truck's emissions-related data is collected. Older trucks may be tested using a different procedure specified by CARB.
Because CARB sets which method applies to which vehicle — and has updated the program over time — confirm your truck's requirements using the official links below.
How to prepare your truck for testing
Preparation doesn't guarantee a result, but it reduces surprises:
- Deal with warning lights first. An active check engine light usually means a stored fault. Consider diagnostics before your test date.
- Don't clear codes right before testing. Clearing codes can reset readiness monitors and doesn't fix the underlying problem.
- Keep up with maintenance. Regular oil changes and preventive maintenance help engines and aftertreatment systems run as designed.
- Test early. Leave time before your deadline to fix a problem and retest.
Reading your results
After testing, we'll explain what the result means for your truck. If the truck has a problem, the result will usually point to a system — not necessarily a specific failed part. That's why diagnosis comes next, not guesswork.
Retesting after repairs
Once the cause has been diagnosed and repaired, your truck can be retested. Follow CARB's requirements for your vehicle. Having testing, diagnosis and repair from the same mobile team keeps this loop short.
Testing multiple trucks
For small fleets, we can test several trucks in one visit to your yard and pair each test with any maintenance that's due. Call (909) 569-3922 to plan several vehicles, or read our maintenance tips for small fleets.
Where we test
Wherever your truck is. We're a mobile tester based in Fremont, CA, and come to trucks in Fremont, Hayward, Oakland, San Jose and across the Bay Area.
CTC testing questions
What is a CARB Clean Truck Check?
Clean Truck Check is the California Air Resources Board's (CARB) heavy-duty vehicle inspection and maintenance program. It requires periodic emissions testing for heavy-duty diesel and other non-gasoline vehicles that operate in California, performed by a CARB-credentialed tester. The goal is to catch emissions-related problems so they get repaired. For the official details, see CARB's Clean Truck Check program page.
How much does a Clean Truck Check cost?
Our Clean Truck Check test is $79, and we come to your truck. You pay when the test is done. CARB's separate annual compliance fee is paid by the vehicle owner directly to CARB and isn't included.
What vehicles can you do a Clean Truck Check on?
Any vehicle that needs one. That includes diesel trucks and tractors, box trucks, dump trucks, buses and shuttles, diesel motorhomes and RVs, agricultural vehicles, and trucks registered in other states. If CARB requires a test for your vehicle, we can come to it and test it — $79.
Does my truck need a Clean Truck Check?
CARB defines which vehicles are covered, and it generally applies to heavy-duty, non-gasoline vehicles operating in California — including many trucks registered out of state. Because the exact rules depend on your vehicle, check CARB's vehicle owner information or call us and we'll point you to the right place to confirm.
How long does a Clean Truck Check take?
It depends on the test method that applies to your truck. An on-board diagnostics (OBD) test is typically a short visit. Older trucks that need a different test method can take longer. We'll give you a time estimate when you book so you can plan your day.
What should I have ready for my Clean Truck Check?
The truck, the keys, and your vehicle information — VIN, license plate and registration. If you've had previous test results or received a notice from CARB, have those handy too. Park somewhere safe where we can reach the truck, and tell us about any warning lights.
What happens if my truck has a problem during testing?
We'll explain what the test found in plain language. Many issues show up as stored fault codes or emissions-related readings. From there, you can have us diagnose the cause and give you a repair estimate. Nothing is repaired without your approval.
Can you diagnose my truck after the test?
Yes. We're a full-service mobile truck mechanic, not just a tester. If testing points to a problem, we can move straight into diagnostics on the spot instead of sending you somewhere else.
Can you perform repairs after a Clean Truck Check?
In many cases, yes. After diagnosis we'll give you a written estimate. If you approve it, we can often do the repair right at your truck. If a repair needs a shop or is outside what we do, we'll tell you so upfront.
Is the CARB compliance fee included in the test price?
No. CARB's annual compliance fee is paid by the vehicle owner directly to CARB through its reporting system. Our $79 price covers the mobile testing service. Check CARB's website for current fee information.
How often does my truck need a Clean Truck Check?
Testing frequency is set by CARB and depends on the vehicle type and CARB's current schedule, which has changed over time. Check CARB's vehicle owner information for your truck's deadlines. We're happy to schedule reminders when you book with us.
If your truck needs more than a test
RV & Motorhome Clean Truck Check
Mobile CARB Clean Truck Check for diesel motorhomes and RVs — we come to your RV park, campground, driveway or storage lot.
$79
Truck Diagnostics
Check engine and warning light diagnostics, electronic troubleshooting, starting and electrical problems — diagnosed before parts are replaced.
Diagnostic pricing confirmed before work begins
Truck Repair
Mobile mechanical and electrical repair for commercial trucks, quoted after diagnosis so you know the cost before work starts.
Quoted after diagnosis
Preventive Maintenance
Scheduled maintenance for owner-operators and small fleets — oil, filters, fluids and inspections planned around your routes.
Priced by maintenance plan
Truck Oil Change
Mobile diesel oil changes with Delo SynBlend or Shell Rotella T6 full synthetic, plus a new filter — done where your truck is parked.
Starting at $500
Book mobile CARB CTC testing — $79
We come to your truck anywhere in the Bay Area.