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Home / News / Newsfeed / Smoke Test Programs for Heavy-Duty Vehicles

Smoke Test Programs for Heavy-Duty Vehicles

January 27, 2023
two heavy duty vehicles in a dirt field

CARB’s Periodic Smoke Inspection Program (PSIP)

The PSIP requires fleets with at least two diesel vehicles with a gross vehicle weight rating (GVWR) over 6,000 pounds to conduct annual smoke tests when the engine is over 3 years old, if driven on California public roads and registered with the California Department of Motor Vehicles (DMV).

CARB’s Heavy-Duty Inspection and Maintenance (HD I/M) Program

In October 2022, CARB adopted the HD I/M Program. Starting in 2023, private and public fleets are required to report their non-gasoline combustion vehicles with a GVWR over 14,000 pounds that operate on California public roads (regardless of which DMV state they are registered in). This expands the smoke test requirements to other fuel types, such as compressed natural gas (CNG) and propane heavy-duty vehicles.

Starting in 2024, there will be a $30 fee per applicable vehicle and smoke tests will be required twice per year. Vehicles with 2013 engine model years and newer can opt for quarterly onboard diagnostics (OBD) reports in lieu of smoke tests. Diesel vehicles 6,001-14,000 pounds will either continue PSIP smoke tests or conduct smog checks every other year, if designated as such.

Smoke Tester Credentials

The smoke testing must be performed by a certified tester, and testers must renew their credentials every 2 years. The free HD I/M tester training course, exam, and associated info can be found at: https://ww2.arb.ca.gov/our-work/programs/inspection-and-maintenance-program/hd-im-tester-training-course-and-exam.

Certified testers can also have their name included on the public list that is linked on the above website.

Table 1: CARB Smoke Test Programs Compliance Summary

Program   Elements PSIP HD I/M Program Notes
Applicability Fuel Type Diesel   Vehicles Non-Gasoline,   Non-ZE Vehicles -
GVWR Over   6,000 lbs Over   14,000 lbs GVWR   6,001-14,000 lbs continue PSIP or bi-ennial smog checks.
DMV California   Registered Any   State -
Age Engine   > 3 Years Old All   Ages -
Operations Public   Roads Public   Roads Vehicles   operated solely on private property are exempt.
Smoke Testing Annually Starting   2024, twice a year if older than 2013 model year. Newer vehicles switch to   OBD reports. -
In-House Testing Free   Online Cerification/Training Renew   credentials every 2 years. -
Reporting N/A Starts   2023. Annual reports twice/year starting 2024. Initial   reporting Q1-Q2 2023 (TBD).
Fees N/A $30/Vehicle -


Yorke Engineering specializes in air quality consulting and environmental consulting for stationary and mobile sources, including dispersion modeling, health risk assessments, permitting, emission inventories, air quality compliance systems, etc. Yorke Engineering has assisted over 1,800 customers, including a wide variety of industrial facilities and government organizations throughout California. Learn more about how we can help you here: Air Quality | Yorke Engineering, LLC (yorkeengr.com).

Main Office:

31726 Rancho Viejo Rd. Suite 218
San Juan Capistrano, CA 92675

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