If you received a CARB Notice to Submit to Testing (NST) for your truck, you have 30 calendar days from the date you receive the notice to submit a passing Clean Truck Check emissions compliance test. The test must be performed by a CARB-credentialed tester.
The important part is not to wait until the end of those 30 days. If your truck fails, you may still need diagnostics, repairs, parts, and enough driving time for the emissions system to complete its required checks before you can successfully retest.
For truck owners and fleet operators in Bakersfield, the best approach is simple: diagnose the problem first, repair what is actually causing it, and then complete the required test.
What Is a CARB Notice to Submit to Testing?
A Notice to Submit to Testing is issued when CARB identifies a vehicle as a potential high emitter through the Clean Truck Check program.
CARB began using Remote Emissions Monitoring Devices (REMDs) together with automated license plate readers in January 2023 to identify vehicles that may have excessive emissions. A vehicle flagged through this system can receive an NST requiring the owner to submit a passing emissions compliance test.
An NST is not simply a routine maintenance reminder. It means CARB is requiring proof that the vehicle’s emissions control system is functioning properly.
Why Did CARB Flag My Truck?
Remote monitoring looks at emissions from vehicles operating on California roads. Two trucks that appear similar from the outside can produce very different emissions readings depending on their engine condition, aftertreatment system, maintenance history, and operating conditions.
A truck with a partially restricted DPF, an emissions sensor problem, an SCR issue, or another aftertreatment fault may produce emissions that cause it to be identified as a potential high emitter.
That is why replacing one component or clearing a diagnostic code without finding the underlying problem is not a reliable strategy.
The 30-Day Clock Is the Part You Cannot Ignore
The deadline is 30 calendar days, not 30 business days. CARB requires the vehicle owner to submit a passing emissions compliance test performed by a credentialed tester within that period.
One of the biggest mistakes is waiting until the final week to schedule a test.
Imagine you take the truck in on day 25 and it fails. You may then need to:
- Identify the actual emissions fault.
- Order or replace components.
- Complete the repair.
- Allow the vehicle to complete the necessary diagnostic checks.
- Return for another test.
That can quickly consume the remaining time.
The better approach is to use the first week for diagnosis and repair planning rather than treating the deadline as a testing appointment date.
What Should You Do During the First Week?
Start with a proper diagnostic inspection.
Bring the NST with you and provide the truck’s VIN and any diagnostic information you already have. A technician can then evaluate the emissions system and determine whether there is an obvious fault that needs attention before testing.
At Flying Bird Truck Repair, commercial truck diagnostics and DPF cleaning are among the services available for truck owners and fleets in Bakersfield.
The objective should be to determine why the truck may be producing excessive emissions, rather than simply attempting a test and hoping it passes.
Which Clean Truck Check Test Does Your Truck Need?
The testing method depends on the vehicle and engine.
OBD Testing
Heavy-duty diesel vehicles with 2013 and newer model-year engines and alternative-fuel vehicles with 2018 and newer engines generally use the Clean Truck Check OBD testing process when they are equipped for OBD testing. The test uses a CARB-certified OBD testing device to retrieve emissions-related information from the vehicle.
The system evaluates information such as diagnostic trouble codes, malfunction indicator status, readiness, and other emissions-related data.
A critical point is that clearing diagnostic codes immediately before testing can create another problem.
CARB explains that a vehicle can be considered “Not Ready” if it has not been driven enough after codes were cleared for its diagnostic monitors to complete their checks. The current requirement is at least five warm-up cycles after codes are cleared.
So clearing a code right before an OBD test does not make the underlying issue disappear. It may actually prevent the vehicle from being ready for the test.
Non-OBD Testing
Older diesel vehicles without the applicable OBD system generally require a different testing process.
For diesel vehicles with 2012 and older engines, CARB requires a smoke opacity test using a compatible smoke meter along with a visual inspection of the vehicle’s emissions control equipment.
The test must be completed through the appropriate Clean Truck Check process by a credentialed tester.
What Can Cause a Truck to Be Flagged?
The cause of an emissions problem is not always the component that first appears in a diagnostic report.
DPF Loading and Incomplete Regeneration
A loaded diesel particulate filter can restrict exhaust flow and affect emissions performance.
Repeated incomplete regenerations, excessive soot production, or an underlying engine problem can contribute to DPF loading.
Cleaning the DPF may solve the problem when the filter itself is the issue. But if something upstream is causing excessive soot, cleaning the filter without addressing that cause may only provide a temporary solution.
NOx Sensors, DEF Dosing and SCR Problems
Modern diesel aftertreatment systems rely on several components working together.
A NOx sensor problem can sometimes make the diagnostic picture look like an SCR efficiency problem. DEF dosing issues, sensor faults, wiring problems, and actual SCR performance problems can produce similar symptoms.
This is where proper diagnostics matter.
Replacing an expensive aftertreatment component based only on one fault code can be an expensive way to approach an emissions problem.
EGR Problems
Exhaust gas recirculation problems can also contribute to emissions-related issues.
A malfunctioning EGR valve or restricted EGR cooler can affect combustion and increase soot production. That additional soot can contribute to DPF loading and repeated regeneration problems.
The emissions system should therefore be diagnosed as a system rather than treating every fault code as an isolated component failure.
Why Clearing the Code Is Not a Fix
Clearing a diagnostic code removes the stored fault information. It does not necessarily repair the mechanical or emissions problem that caused the code.
CARB also warns that recently cleared codes can leave an OBD vehicle in a “Not Ready” condition until enough operation has occurred for the required monitors to complete.
If your truck received an NST, the goal should be to repair the cause and establish that the repair worked before submitting the compliance test.
What Happens If You Miss the NST Deadline?
Ignoring an NST can create more than a repair problem.
CARB states that vehicles that do not comply may face enforcement action, penalties, and registration holds. California Health and Safety Code §42402 provides for potential civil penalties ranging from $1,000 to $10,000 per day per vehicle, depending on the violation and applicable circumstances.
There are also serious penalties associated with tampering with emissions-control equipment. CARB states that illegal modification or tampering can result in penalties of up to $37,500 per violation.
For commercial operators, a registration hold can become a major operational problem because keeping trucks legally registered is essential to keeping a fleet moving.
CARB and the California Highway Patrol also have enforcement responsibilities associated with Clean Truck Check.
How Do You Clear a Clean Truck Check Registration Hold?
If your vehicle has a Clean Truck Check-related registration issue, the first step is to bring the vehicle back into compliance.
Once the required passing information is properly submitted, CARB updates its compliance records and communicates compliant vehicle information to DMV through the Clean Truck Check system.
Do not assume that completing a repair immediately means the DMV record will update instantly. Give the agencies time to process the compliance information and check the vehicle’s status before your registration deadline.
If you are dealing with an active registration hold, verify the current status through the official CARB Clean Truck Check system rather than relying on an old deadline or fee figure published elsewhere.
What If You Only Operate in California Occasionally?
Out-of-state operators should not assume that being registered outside California removes Clean Truck Check obligations.
CARB states that Clean Truck Check applies to covered heavy-duty vehicles operating on California public roads, including vehicles that are not registered in California.
CARB also provides a Five-Day Pass process for eligible vehicles that need to operate in California briefly. The current eligibility and request requirements should be checked directly with CARB before travel.
If your truck regularly enters California, keeping its Clean Truck Check requirements current is generally safer than trying to solve a compliance issue after the vehicle has already been flagged.
What We Recommend When an NST Comes In
When you receive a CARB Notice to Submit to Testing, don’t wait until the deadline is approaching.
Bring the notice, VIN, and any diagnostic information or fault codes with you.
At Flying Bird Truck Repair in Bakersfield, our truck repair services include commercial diagnostics, DPF cleaning, maintenance, and 90-day BIT inspections.
Our approach should be straightforward:
Diagnose → Repair → Verify → Test
That sequence gives you a better opportunity to identify the actual problem before submitting the required emissions compliance test.
If the truck needs DPF service, diagnostics, or another repair, addressing the issue before the test can help avoid losing valuable time to a failed submission.
Frequently Asked Questions
How many days do I have after receiving a CARB NST?
You have 30 calendar days from receipt of the Notice to Submit to Testing to submit a passing emissions compliance test.
Can I test my own truck?
Only an appropriately credentialed Clean Truck Check tester can perform and submit the applicable emissions compliance testing. CARB provides a free tester training and examination process for people who want to become credentialed.
What happens if my truck fails the Clean Truck Check test?
You need to identify and correct the underlying emissions problem and then complete another applicable test. With OBD testing, repairs or clearing codes can also affect readiness, so the vehicle may need sufficient operation before it can successfully complete the test.
Will DPF cleaning make my truck pass?
It can help when excessive DPF loading is contributing to the emissions problem, but it is not a guaranteed solution for every NST. Sensor faults, SCR problems, EGR issues, fuel-system problems, and other conditions can also contribute to emissions failures.
Does Clean Truck Check apply to out-of-state trucks?
Yes. Covered heavy-duty vehicles operating on California public roads can be subject to Clean Truck Check requirements even when they are registered outside California.
How much is the Clean Truck Check annual compliance fee?
The amount can change, so operators should verify the current fee directly through the official CTC-VIS system rather than relying on an outdated number published in a blog.
Don’t Wait Until Day 25
A CARB Notice to Submit to Testing gives you a deadline, but it does not give you unlimited time for repairs.
If your truck has been flagged, start with a proper diagnosis. Find the reason for the emissions problem, complete the necessary repair, make sure the vehicle is ready for testing, and then submit the required passing test through the Clean Truck Check process.
Bring us the notice and the VIN. Thirty days is enough — if you start now.
For commercial truck diagnostics, DPF cleaning, and truck repair in Bakersfield, contact Flying Bird Truck Repair.
Flying Bird Truck Repair
681 Pepper Dr, Bakersfield, CA 93307
661-567-0020
Important Compliance Note
This article is intended as general information for truck owners and fleet operators. Clean Truck Check requirements and enforcement procedures can change. Flying Bird Truck Repair provides truck repair and diagnostic services, not legal or regulatory consulting. For a vehicle-specific compliance determination, verify the current requirements through CARB and, where applicable, the California Highway Patrol.
