Know your test type. Arrive prepared.

Looking for a specific answer? Browse questions about preparation, test results, CTC-VIS and fleet scheduling.

1. Check whether your vehicle is covered

Clean Truck Check generally applies to diesel and alternative-fuel vehicles over 14,000 pounds GVWR operating on California public roads, including many vehicles registered in other states. Exemptions and special cases apply. Do not assume that private ownership or personal use makes a California-registered diesel motorhome exempt.

Source: CARB CTC-VIS user guide and CARB program FAQ.

2. Match the test to the engine

• 2013 and newer diesel engines: generally an OBD test using a CARB-certified testing device.
• 2012 and older diesel engines: generally smoke opacity testing plus an emissions-control equipment visual inspection.
• 2018 and newer alternative-fuel engines: generally an OBD test.
• 2017 and older alternative-fuel engines: generally a visual inspection only, not a smoke opacity test.

The engine model year can differ from the truck model year. Engine replacements and vehicles using off-road engines need special attention; confirm the method before booking rather than guessing from the registration year.

Source: CARB emissions compliance testing requirements.

3. Look up the real deadline

Use the deadline shown for your vehicle in CTC-VIS, not a generic online calculator. Most covered vehicles test every six months. Qualifying agricultural vehicles and California-registered non-commercial motorhomes follow annual requirements.

CARB currently lists October 2027 for the move to four OBD tests per year, with those annual exceptions unchanged. Passing tests can generally be submitted up to 90 days before the applicable deadline. Check current CARB guidance when planning future appointments.

Source: CARB semi-annual compliance requirements and annual requirements for qualifying vehicles.

4. Have these details ready

• Vehicle identification number, license plate, engine model year and fuel type.
• The CTC-VIS due date and any previous failed-test report.
• Your appointment address and an on-site contact for mobile service.
• Details of warning lights, recent repairs or engine changes.

Do not send account passwords in an email or website form. Ask our team about the appropriate authorization process for portal assistance.

5. Understand what a passing test does not replace

A passing emissions test is one part of Clean Truck Check compliance. Vehicle reporting, annual CARB compliance fees and other outstanding requirements also matter. The VIN in CTC-VIS should match the vehicle record.

If a test fails, review the reason for the failure and address the issue before arranging a retest. Do not clear fault codes or disconnect the battery merely to try to pass; ask the tester or repair provider how recent work may affect readiness.

Source: CARB vehicle reporting guidance. For an official determination, contact CARB.