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Diesel Truck Emissions California Compliance Guide

Discover how to navigate diesel truck emissions California standards effectively. Our guide ensures your fleet stays compliant with CARB regulations, avoiding penalties and maintaining operational efficiency. Learn about the Truck & Bus Regulation, Clean Truck Check, and essential compliance steps designed to reduce harmful emissions. From reporting requirements to flexibility options, we provide all the details you need for seamless compliance. Trust us to help you meet California's air quality standards while keeping your business on the move.

Bus and Truck parked next to each other for clean truck check truck and bus regulations

Who’s Covered & Who’s Exempt

 

Covered Vehicles

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  • Diesel trucks and buses with a gross vehicle weight rating (GVWR) over 14,000 lbs. 

  • Privately or federally owned, leased, or operated. 

  • School buses (diesel) that carry pupils (grades K–12) are subject as well. 

 

Exemptions & Special Cases

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Some vehicles are not subject to the regulation (or qualify for reporting exemptions) including:

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  • Vehicles powered exclusively by gasoline or alternative fuels (non-diesel) 

  • Certain public agency or utility vehicles (non-federal) California Air Resources Board+1

  • Drayage trucks (port or rail drayage) — at least until certain dates 

  • Personal-use motorhomes, vehicles used exclusively for snow removal, or those converted to natural gas or gasoline, etc. 

  • Pick-up trucks with GVWR ≤ 19,500 lbs used strictly for personal, noncommercial use 

Some vehicles that appear exempt still have to file in Excluded Diesel Vehicle Reporting (EDVR) to avoid DMV registration holds.

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Compliance Requirements & Schedule

Engine Model Year (EMY) Requirements

 

Vehicles must comply with a schedule determined by their engine model year (EMY). Older engines must be replaced or repowered (i.e. new engine) by set dates unless exempt or using an allowable option. 

 

For example:
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GVWR Category EMY Range Deadline to Replace / Repower

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  • 14,001 – 26,000 lbs2000 – 2003 (EMY)Jan 1, 2020 

  • 14,001 – 26,000 lbs2007 – 2009Jan 1, 2023 

  • 26,000 lbs1996 – 1999Jan 1, 2020 

  •  26,000 lbs2007 – 2009Jan 1, 2023

 

Note: The regulation controls engine model year (EMY), but DMV may use the vehicle model year for registration denial assumptions. 

 

Emission Control Devices & Filters

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For larger vehicles, compliance may also require verified diesel emission control strategies (VDECS) or particulate filters, depending on weight class and engine vintage. 

Proper maintenance and documentation of filters or retrofits is also required.

 

Reporting & Verification

TRUCRS Reporting System

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Fleet owners use TRUCRS (Truck Regulation Upload, Compliance, and Reporting System) to submit required data and report compliance status.

You’ll need to enter fleet, vehicle, and engine data, and optionally report use of flexibility options, exemptions, or EDVR status. 

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DMV Registration Verification

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Starting January 1, 2020, DMV began automatic checks for compliance. If a vehicle is non-compliant or not properly reported, the registration may be denied. 

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If a vehicle is out of compliance, you may qualify for a 90-day Temporary Operating Permit (TOP) from DMV while you achieve compliance. However, a TOP does not count as compliance under the regulation. 

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Flexibility Options & Extensions

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  • Manufacturer Delay Extension: If you have already ordered a compliant replacement or retrofit that is delayed by the manufacturer, you may temporarily continue operating the older vehicle under rules and documentation. 

  • Low-Use Exemption: Vehicles that operate less than 1,000 miles annually in California may qualify for a low-use exemption. 

  • NOx Exempt Area Flexibility: In limited cases, fleets in certain areas may use filters and limit operations in certain zones under NOx flexibility provisions. Some previous flexibility provisions have been phased out or restricted over time. 

 

Consequences of Non-Compliance

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  • Registration Denial or Hold: Non-compliant vehicles may be blocked from registering or renewing registration with DMV. 

  • Operating Penalties: Operating a non-compliant vehicle may lead to fines or enforcement actions under California air quality laws. 

  • Disclosure Obligations: If selling a non-compliant vehicle in California, the seller must provide a written disclosure about its non-compliance. 

 

Useful Resources & Additional Details

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  • CARB’s official Truck & Bus Regulation fact sheets and compliance guides 

  • The full regulation text (Title 13, section on Truck & Bus)

  • Compliance overview PDF from CARB 

  • CARB’s “Guide to California’s Clean Air Regulations for Heavy-Duty Diesel Vehicles”

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Source: California Air Resource Board (CARB)

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