California Air Resources Board

This Fact Sheet presents an overview of the requirements for credentialed testers who are authorized to perform emissions compliance testing within the Clean Truck Check program.

How to Become a Credentialed Tester

Anyone can become a credentialed tester and may be employed by a fleet and are responsible for testing fleet vehicles, or will offer for-hire services (third-party testers) either as an independent business owner or as an employee of a heavy-duty vehicle service facility. You must simply take the Tester Training Course and pass the exam.

How do I register for the Tester Training Course?

On the Tester Training Course webpage, you may register for access to the course. Please ensure the accuracy of all information when completing the registration form. You must register using an email address that is unique to you. Do not register using an email address shared by multiple people. The email address used to register for the exam must match the email address used to log in to your testing device. Any discrepancies in email addresses will cause an invalid tester ID error, and the test will not be accepted.

You may choose to be listed on the "Available for Hire Credentialed Testers" list when registering. If you want to be on the credentialed testers for hire list that is available to the public after receiving your certificate , please send an email to hdim@arb.ca.govwith your contact information (first and last name, business name and address, email, phone number) and a copy of your Clean Truck Check Credentialed Tester Training Certificate if possible and request to be added to the list. CARB staff will update the list regularly and your contact information will appear in the next update.

How do I update/change my tester information?

If you need to edit your tester information please email hdim@arb.ca.gov and include: information (first and last name, business name and address, previous email and , phone number) and a copy of your Clean Truck Check Credentialed Tester Training Certificate if possible.

What topics will the Tester Training Course cover?

The training course and exam will educate you on the regulatory requirements and how to perform the different types of emissions compliance testing. There are six modules posted on the Tester Training Course webpage:

• Module I: Purpose and Expectations
• Module II: Basic Regulatory Requirements
• Module III: On-Board Diagnostics (OBD) and OBD Compliance Testing
• Module IV: SAE J1667 Smoke Opacity Testing
• Module V: Vehicle Emissions Control Equipment Inspection (Visual Inspection)
• Module VI: How to access the Clean Truck Check (HD I/M) Tester Exam and, upon successful completion, how to obtain your Certificate of Completion.

Completing the six training modules takes approximately two hours.

How do I get my certificate once I pass the test?

After completing the six training modules, you will be directed to a 20-question multiple-choice exam. A minimum score of 80 percent is required to pass the exam. After passing the exam, you will be provided with an electronic version of your certificate to download and print immediately after you pass the exam. Please retain the certificate for your records. Please email hdim@arb.ca.gov from the email address used to register for the tester training if you need a copy of your certificate again.

Does my Certificate of Completion ever expire? How do I renew it?

Your certificate is valid for two years from the date you passed the exam. The expiration date is located at the bottom right of your Certificate. To renew your certificate, you must retake the Tester Training Course and pass the exam again. You can watch the six training modules for review purposes at the Clean Truck Check (HD I/M) Tester Training Modules section on the Diesel Regulation Training Course Video Archive website. You will be issued a new tester ID upon renewal. If you wish to continue using the current login for your OBD test devices, be sure to use the same email address during training registration.

Can I do OBD Testing and Non-OBD Testing?

You may perform emissions compliance testing for OBD-equipped vehicles and you must use CARB-certified OBD test devices for this testing. You have to submit the first OBD test result to appear as "Yes" for OBD testing capability on the public "Available for Hire Credentialed Testers" list.

To perform emissions compliance testing for non-OBD-equipped vehicles, you may continue to use your current SAE J1667-compatible smoke meters to complete the required opacity test and use the Vehicle Emissions Control Equipment Inspection Form to conduct a visual inspection.

Can I share my credentials with co-workers who also want to perform emissions compliance testing?

No. The email address used to register for the Tester Training Course and exam should be unique to you and used only for tests you submit. Every credentialed tester must take the Tester Training Course and pass the exam to obtain their own certificate.

How do I update my credentialed tester contact information (company name, email address, phone number, etc.)?

Please note that if you want to update your tester account with a NEW email address, you will also need to work with your OBD test device vendor to update your email address with them as well.

Please reach out to CARB staff and notify us of your requested changes by sending an email request to hdim@arb.ca.gov. We will update our internal records to reflect the new information associated with your Credentialed Tester ID. Please allow a couple of business days for the change to take effect in our internal records.

We will also update your contact information on our Available for Hire Credentialed Testers webpage. Please note that these updates are made biweekly.

How do I remove myself from the public tester list?

Please send an email to hdim@arb.ca.gov with your contact information and request to be removed from the list. CARB staff updates the list regularly.

Is there a Clean Truck Check logo I can use for marketing?

CARB has developed materials to assist Credentialed Clean Truck Check (CTC) Testers. This material is available for download at Clean Truck Check Credentialed Testers Marketing Materials | California Air Resources Board. You are encouraged to use it at your business.

The CARB Clean Truck Check logo is provided in the link below. Use of CARB logos that are not authorized will result in receipt of a “cease and desist” letter due to the unauthorized use of the logo. 

Emissions Compliance Testing

What are the testing requirements for Clean Truck Check?

Starting October 1, 2024, emissions compliance testing will be required for all vehicles subject to Clean Truck Check. Vehicle compliance deadlines begin January 1, 2025. Vehicles may submit passing tests up to 90 days prior to the vehicle’s compliance deadlines. A factsheet is available in the link below. 

• Vehicle Owners: Emissions Compliance Testing Requirements

Do you have to be a credentialed tester to perform OBD tests using a telematics device?

No, the test results from telematics devices are automatically provided.

How do I know if I should do an OBD or non-OBD test?

OBD-equipped vehicles (2013 and newer diesel engines and 2018 or newer alternative fuel engines) are required to undergo a scan of the engine’s OBD data using a CARB-certified OBD test device.

Non-OBD-equipped vehicles (2012 and older diesel engines and 2017 and older alternative fuel engines) are required to undergo testing as noted in the following question.

What testing equipment do I need to perform emissions compliance testing?

To perform OBD compliance tests, a credentialed tester must use a CARB-certified OBD test device. A list of CARB-certified OBD test devices is available at OBD Test Devices. CARB’s webpage will continually be updated as devices become approved for use in the program. Using an OBD test device that is not certified by CARB will result in an unsuccessful test for the vehicle on which it is used. More information on OBD testing can be found at OBD Readiness Criteria | California Air Resources Board.

Diesel non-OBD vehicles are required to complete a smoke opacity test and a visual inspection of the vehicle’s emissions control equipment, referred to in this program as the Vehicle Emissions Control Equipment Inspection. Alternative fuel non-OBD vehicles are only required to complete the visual inspection and are not subject to the smoke opacity test requirement.

To perform smoke opacity testing, you will need an SAE J1667-compatible smoke meter. A list of manufacturers that sell SAE J1667-compatible smoke meters and their contact information is available at Smoke Meter Manufacturers. If you already have an SAE J1667-compatible smoke meter, you may continue to use that for emissions compliance testing on non-OBD-equipped vehicles. It is the responsibility of a credentialed Clean Truck Check Tester to coordinate with a smoke meter manufacturer to ensure that their specific smoke meter model is SAE J1667-compatible. The SAE J1667 Recommended Practice Snap Acceleration Smoke Test Procedure for Heavy-Duty Powered Vehicles is also available here.

To perform the Vehicle Emissions Control Equipment Inspection, you will need access to reliable sources of engine and vehicle technical specifications, such as service and repair manuals. The current form for completing and submitting results to CARB is available at Vehicle Emissions Control Equipment Inspection Form. Please read the information and instructions document to accurately complete and submit the separate Vehicle Emissions Control Equipment Inspection Form.

How do I create a tester account and submit and review test results?

You need to create a tester account in the Clean Truck Check-Vehicle Inspection System (CTC-VIS). To create a tester account in CTC-VIS, please select “Credentialed Tester Account” from the “Account Type” dropdown menu during the registration process. For detailed instructions, please refer to the Credentialed Tester Account User Guide. A video is available at Create A CTC-VIS Account To View/Review Test Results

OBD data collected by CARB-certified OBD test devices will be automatically transmitted to a centralized database maintained by the OBD device vendor. All OBD data submissions to CARB must come from the OBD device vendor. You can view OBD test results on the Test Results page in your credentialed tester account. Each test result is a hyperlink that displays the associated Test Result message in a popup dialog box when you click on it.

For non-OBD-equipped vehicles, forms associated with emissions compliance testing must be submitted to non-obd-test-submission@arb.ca.gov. Please refer to the Instructions for the Vehicle Emissions Control Equipment Inspection Form for detailed instructions. Non-OBD test results are not available in your credentialed tester account at this time.

PDFs of test results will no longer be provided by email. The test result now appears in the tester’s and vehicle owner’s accounts.

Can we create a Company account to view test results from all of our Credentialed Testers?

Each tester must have their own account to view their results. As the results are based on the tester ID and email address, their test results are only visible under their individual CTC-VIS account.

How can I receive updates on Clean Truck Check activities?

Subscribe to receive automatic email updates on Clean Truck Check implementation and other activities.

Where do I get additional Clean Truck Check information?

For more information, visit Clean Truck Check (HD I/M).

If I have additional questions, how do I contact CARB?

Please email staff at hdim@arb.ca.gov.