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Truck & Bus Regulation
Regulation Text




Regulation Basics & Exemptions

Diesel trucks and buses with a gross vehicle weight rating(GVWR) that are greater than 14,000 pounds (lbs), must reduce exhaust emissions by meeting particulate matter (PM) filter requirements and upgrading to a 2010 or newer engine model year (EMY).

The Regulation applies to:

  • Diesel vehicles with a GVWR greater than 14,000 lbs.
  • Privately and federally owned trucks and buses that operate in California
  • Any person, business, school district, tribal reservation, or federal government agency that owns, operates, leases or rents affected vehicles.
The Regulation does not apply to:


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Manufacturer Delay Extension

What does the regulation require?
If you own a diesel vehicle, the regulation requires you to take steps to reduce emissions. Nearly all diesel vehicles with a manufacturer’s gross vehicle weight rating greater than 14,000 pounds that operate in California are required to meet certain compliance requirements per the regulation. To comply with these requirements, you can upgrade to 2010 model year or newer diesel engines, or to vehicles that operate on other fuels. You may also be able to purchase a replacement engine to repower your older vehicle.

What is the manufacturer delay extension?
If a vehicle owner has a vehicle that must be replaced or upgraded to meet Truck and Bus regulatory requirements, and the vehicle owner has purchased the necessary replacement or upgrade, the manufacturer delay extension specified in section 2025(p)(8) of the regulation allows the vehicle owner to continue to use the existing vehicle if the replacement or upgrade is unavailable due to a manufacturer delay. You must have purchased the replacement engine or replacement vehicle on or before September 1 before the initial compliance date for the existing vehicle that is to be replaced or upgraded. If the delivery of a replacement vehicle (or replacement engine) is delayed by the manufacturer, then the vehicle owner may continue to operate temporarily the existing vehicle that is to be replaced until the replacement vehicle or engine is delivered. During the open reporting period in January, you must meet the applicable reporting and record keeping requirements of sections 2025(r) and (s) of the regulation and submit proof of the purchase to use the extension. The vehicle owner cannot continue to operate the existing non-compliant vehicle once the replacement vehicle is delivered.

What purchase agreements qualify?
The purchase agreement used to qualify for the manufacturer delay extension must be a written and legally binding contract signed on or before September 1 before the initial compliance date for the vehicle being replaced. The purchase contract must identify that a specific compliant vehicle or specific engine was purchased, the date of the purchase, and it must be for immediate delivery or delivery by December 31 or earlier. Letters of intent or other agreements that are not binding or are contingent upon other decisions that remain unresolved as of September 1 are not sufficient to qualify for the extension.

What if I cancel a purchase agreement?
If a vehicle owner claims the manufacturer delay extension and later the vehicle owner cancels the original purchase agreement used to qualify for the extension, the claim for the extension will be treated as invalid, the vehicle owner will be out of compliance as if the agreement was never executed, and the vehicle owner could be subject to enforcement action. The manufacture delay extension cannot be claimed if you modify the original purchase agreement after September 1. If a vehicle manufacturer cancels an existing purchase agreement or makes changes beyond the purchaser’s control, the owner must contact CARB immediately for assistance with the manufacturer delay extension.

Do I have to meet reporting requirements?
Yes, you must report in CARB’s Truck Regulation Upload, Compliance, and Reporting System (TRUCRS) to take advantage of compliance flexibility each January. The vehicle owner must report by January 31 of the applicable compliance year to claim the manufacturer delay extension for the affected vehicle. The vehicle owner must report information about the vehicle to be replaced or repowered and the date the new equipment order was made. The vehicle owner must also keep records of the purchase and make the records available to CARB staff upon request. The owner has 30 days from receipt of the replacement vehicle or engine to report the appropriate changes to the fleet to demonstrate compliance. In the case of an engine replacement, the vehicle owner must update the vehicle information to identify the new engine and OEM filter installed in the affected vehicle. In the case that the vehicle is replaced, the owner must report information about the replacement vehicle and the date the non-compliant vehicle is sold, scrapped, or retired.

Does the manufacturer delay extension impact grant funding?
During the manufacturer delay extension period, the vehicle that is to be replaced and qualifies for the manufacturer delay extension is treated the same as if it is compliant with the regulation.

Where can I get more information?
You can obtain additional information, at the Truck and Bus Regulation program page, or by calling 866-6DIESEL (866-634-3735), or by emailing the 8666 Diesel Hotline (8666diesel@arb.ca.gov). Contact us if wish to obtain this document in an alternative format or language. TTY/TDD/ Speech to Speech users may dial 711 for the California Relay Service.

Printable Manufacturer Delay Factsheet



Cummins Recall
On August 1, 2018, Cummins initiated a recall of the Selective Catalytic Reduction (SCR) unit catalysts in their 2010 to 2015 model year medium and heavy-duty engines. This recall affects over 500,000 heavy-duty vehicles nationwide. Customer letters for the first phase of the recall were sent to vehicle owners by Cummins starting August 1. Vehicles are to be brought to a Cummins certified service location for replacement catalysts and/or software upgrades.

For assistance, including locating your nearest Cummins certified service location or determining whether your engine is covered by the recall, please contact Cummins Care on the web at https://care.cummins.com or call Cummins at 1-800-CUMMINS (1-800-286-6467).

• Cummins will reimburse cost of previously replaced catalyst.

• California Department of Motor Vehicles may require the completion of emission campaign repairs prior to vehicle registration renewal.

• Cummins will phase-in recalls over time due to the large number of engine families involved. Some recalls will take effect in 2019 as shown in the table below. The table will be updated, as new engine families are included in the recall campaign.

• For 2010-2012 model year ISX 15 Engine Families ACEXH0912XAP, BCEXH0912XAP, and CCEXH0912XAP, and 2013 model year Engine Family DCEXH0912XAT, SCR replacement will occur when the SCR catalyst fails (triggers applicable engine lights/fault codes) within useful life beginning Aug. 1, 2018. Customer letters forthese four engine families only will not be mailed out.

• If your engine family is not listed below and you replaced your catalyst or if you have additional questions, please contact the Diesel Hotline at 1-866-634-3735.

Engine Model Year

Engine Size (Liters)

Cummins Engine

Engine Family

Date Recall Takes Effect

2010

6.7

ISB

ACEXH0408BAH

03/24/2019

6.7

RAM 3500 Cab Chassis

ACEXH0408BAK

01/08/19

6.7

RAM 4500/5500 Cab Chassis

ACEXH0408BAL

1Q2019

6.7

ISB - Urban Bus Hybrid

ACEXH0408BAN

03/24/2019

8.3

ISC

ACEXH0505CAC

03/24/2019

8.9

ISL9

ACEXH0540LAQ

03/24/2019

8.9

ISL9 - Urban Bus

ACEXH0540LAR

03/24/2019

11.9

ISX 12

ACEXH0729XAA

09/28/2018

11.9

ISX 12

ACEXH0729XAB

09/28/2018

11.9

ISX 12

ACEXH0729XAC

09/28/2018

14.9

ISX 15

ACEXH0912XAQ

08/01/2018

14.9

ISX 15

ACEXH0912XAR

09/28/2018

2011

6.7

ISB

BCEXH0408BAH

03/24/2019

6.7

RAM 3500 Cab Chassis

BCEXH0408BAK

01/08/19

6.7

RAM 4500/5500 Cab Chassis

BCEXH0408BAL

01/08/19

6.7

ISB - Urban Bus Hybrid

BCEXH0408BAN

03/24/2019

8.3

ISC

BCEXH0505CAC

03/24/2019

8.9

ISL9

BCEXH0540LAQ

03/24/2019

8.9

ISL9 - Urban Bus

BCEXH0540LAR

03/24/2019

8.9

ISL9

BCEXH0540LAS

03/24/2019

11.9

ISX 12

BCEXH0729XAA

09/28/2018

11.9

ISX 12

BCEXH0729XAB

09/28/2018

11.9

ISX 12

BCEXH0729XAC

09/28/2018

11.9

ISX 12 – Urban Bus

BCEXH0729XAD

09/28/2018

14.9

ISX 15

BCEXH0912XAQ

08/01/2018

14.9

ISX 15

BCEXH0912XAR

09/28/2018

14.9

ISX 15

BCEXH0912XAS

08/01/2018

2012

6.7

ISB

CCEXH0408BAH

03/24/2019

6.7

RAM 3500 Cab Chassis

CCEXH0408BAK

01/08/19

6.7

RAM 4500/5500 Cab Chassis

CCEXH0408BAL

01/08/19

6.7

ISB - Urban Bus Hybrid

CCEXH0408BAN

03/24/2019

6.7

ISB

CCEXH0408BAO

03/24/2019

8.3

ISC

CCEXH0505CAC

03/24/2019

8.9

ISL9

CCEXH0540LAQ

03/24/2019

8.9

ISL9 - Urban Bus

CCEXH0540LAR

03/24/2019

8.9

ISL9

CCEXH0540LAS

03/24/2019

11.9

ISX 12

CCEXH0729XAA

09/28/2018

11.9

ISX 12

CCEXH0729XAB

09/28/2018

11.9

ISX 12

CCEXH0729XAC

09/28/2018

11.9

ISX 12 - Urban Bus

CCEXH0729XAD

09/28/2018

14.9

ISX 15

CCEXH0912XAQ

08/01/2018

14.9

ISX 15

CCEXH0912XAR

09/28/2018

14.9

ISX 15

CCEXH0912XAS

08/01/2018

2013

6.7

RAM 2500-3500 (MDV)

DCEXD06.78VV

2017

6.7

RAM 3500 (MDV)

DCEXD06.78WV

2017

6.7

ISB, ISB Hybrid

DCEXH0408BAP

03/24/2019

6.7

ISB Hybrid

DCEXH0408BAR

03/24/2019

6.7

RAM 3500 Cab Chassis

DCEXH0408BAQ

01/08/19

6.7

RAM 4500/5500 Cab Chassis

DCEXH0408BAS

01/08/19

8.9

ISL9, ISL9 Hybrid (Urban Bus)

DCEXH0540LAT

2017

8.9

ISL9, ISL9 Hybrid

DCEXH0540LAV

03/24/2019

11.9

ISX 12

DCEXH0729XAE

09/28/2018

11.9

ISX 12 Urban Bus

DCEXH0729XAF

09/28/2018

2014

6.7

RAM 2500-3500 (MDV)

ECEXD06.78VV

2017

6.7

RAM 3500 (MDV)

ECEXD06.78WV

2017

6.7

ISB, ISB Hybrid

ECEXH0408BAP

03/24/2019

6.7

ISB Hybrid

ECEXH0408BAR

03/24/2019

6.7

RAM 3500 Cab Chassis

ECEXH0408BAQ

01/08/19

6.7

RAM 4500/5500 Cab Chassis

ECEXH0408BAS

01/08/19

8.9

ISL9, ISL9 Hybrid (Urban Bus)

ECEXH0540LAT

2017

8.9

ISL9, ISL9 Hybrid

ECEXH0540LAV

03/24/2019

2015

6.7

RAM 2500-3500 (MDV)

FCEXD06.78VV

2017

6.7

RAM 3500 (MDV)

FCEXD06.78WV

2017

6.7

RAM 3500 Cab Chassis

FCEXH0408BAQ

01/08/19

6.7

RAM 4500/5500 Cab Chassis

FCEXH0408BAS

01/08/19



Regulation Requirements

The Regulation compliance schedule is based on the year of the current engine(s). Older vehicles will need to be replaced or repowered with a 2010 or newer engine following the schedule below, unless it is exempt from the Regulation. There are also filter requirements for larger vehicles.

There are two schedules, one for lighter vehicles and one for heavier vehicles. Inspect the vehicle’s door jamb to determine the GVWR and if it falls in the lighter or heavier category.

Lighter vehicles between 14,001 and 26,000lbs GVWR: 1995 and older model year engines need to be replaced or repowered by 1/1/15. 1996 model year engines need to be replaced or repowered by 1/1/16. 1997 and older model year engines need to be replaced or repowered by 1/1/17. 1999 and older engines need to be replaced or repowered by 1/1/19. 2000-2003 model year engines need to be replaced or repowered by 1/1/20. 2004-2006 model year engines need to be replaced or repowered by 1/1/21. 2007-2009 model year engines need to be replaced by 1/1/23.Heavy vehicles above 26,000lbs GVWR: 1993 and older model year engines need no particulate matter filter, but require repower or replacement by 1/1/15. 1994-1995 model year engines require no particulate filter, but require repower or replacement by 1/1/16. 1996-1999 model year engines required a particulate matter filter by 1/1/12, and will require a repower or replacement by 1/1/20. 2000-2004 model year engines required a particulate matter filter by 1/1/13, and require a repower or replacement by 1/1/21. 2005-2006 model year engines required a particulate matter filter by 1/1/14, and will require a repower or replacement by 1/1/22. 2007-2009 model year engines required a particulate matter filter by 1/1/14 if not allready manufacturer-equipped, and require repower or replacement by 1/1/23.
Lighter vehicles between 14,001 and 26,000lbs GVWR: 1995 and older model year engines need to be replaced or repowered by 1/1/15. 1996 model year engines need to be replaced or repowered by 1/1/16. 1997 and older model year engines need to be replaced or repowered by 1/1/17. 1999 and older engines need to be replaced or repowered by 1/1/19. 2000-2003 model year engines need to be replaced or repowered by 1/1/20. 2004-2006 model year engines need to be replaced or repowered by 1/1/21. 2007-2009 model year engines need to be replaced by 1/1/23. 
Heavy vehicles above 26,000lbs GVWR: 1993 and older model year engines need no particulate matter filter, but require repower or replacement by 1/1/15. 1994-1995 model year engines require no particulate filter, but require repower or replacement by 1/1/16. 1996-1999 model year engines required a particulate matter filter by 1/1/12, and will require a repower or replacement by 1/1/20. 2000-2004 model year engines required a particulate matter filter by 1/1/13, and require a repower or replacement by 1/1/21. 2005-2006 model year engines required a particulate matter filter by 1/1/14, and will require a repower or replacement by 1/1/22. 2007-2009 model year engines required a particulate matter filter by 1/1/14 if not allready manufacturer-equipped, and require repower or replacement by 1/1/23.

Note: Engines are manufactured separately from the vehicle chassis and typically are one year older than the vehicle model year (VMY). The Regulation regulates the engine model year (EMY) but DMV registration will be denied based on VMY, with the assumption that VMY is one year newer than the EMY. If the EMY is not one year older than the VMY, extra steps may be necessary to avoid early registration denial.

Check Engine Compliance ►
Find out if or when your vehicle is subject to DMV registration denials or holds.



School Buses
School bus vehicles powered by diesel fuel with a gross vehicle weight rating (GVWR) of greater than 14,000 pounds that provide transportation of any school pupil at or below the 12th-grade level or to or from a public or private school, or to or from public or private school activities are subject to the Truck and Bus Regulation.

Previously, school buses that could not be retrofitted (e.g. 2-stroke engine buses), could delay their compliance until January 1, 2018 with an approved extension.

School Bus Fact Sheet
School Bus Idling Fact Sheet

School Bus Funding ►
School Bus Webinar ►


Flexibilty Options

Currently, there are limited options available. These options require reporting in CARB's TRUCRS reporting system. If a vehicle does not qualify for these options, it must follow the engine model year compliance schedule.

Low-Use Exemption:
Low-use vehicles are vehicles that travel less than 1,000 miles per year, including vehicles that are not operated (even if they have a non-op registration). A vehicle that travels more than 1,000 miles annually can use the low-use vehicle exemption as long as it operates less than 1,000 miles within California each year. The low-use option allows the vehicle to be exempt from PM filter and engine replacement requirements. Annual odometer reporting in TRUCRS is required to demonstrate compliance with this option. Third party records must be kept and provided upon request to obtain and maintain this exemption.

Low-use Exemption Fact Sheet

NOx Exempt Area Flexibility Option:
Beginning January 1, 2020, vehicles can remain under the NOx Exempt Area option and avoid vehicle replacement or they can be upgraded based on the Engine Model Year Compliance Schedule to operate statewide. Annual reporting in TRUCRS is required to demonstrate compliance with this option. There are limited circumstances under which a PM filter can be newly installed on a vehicle and be considered to meet the final requirements of the regulation if they operate solely in NOx Exempt Areas. Eligibility must first be determined.

NOx Exemption Area Fact Sheet






Lawson Lawsuit

In 2014, to void the flexibility options provided in the 2014 amendments to the Regulation, John R. Lawson Rock and Oil of Fresno (Lawson) and the California Trucking Association (CTA) sued CARB in Fresno County Superior court.

In 2016, that court ruled in favor of Lawson and CTA, ordering CARB to set aside the regulation’s 2014 amendments. CARB appealed that decision to the 5th District court of Appeals. On January 31, 2018, the appellate court issued its decision upholding parts of the lower court’s ruling, including the court’s direction to set aside the regulation’s 2014 amendments.

If vehicles in your fleet are using one or more of the flexibility options that CARB added or amended in 2014, you will be impacted by the court’s decision.

More Information ►



DMV Compliance Verification

Beginning January 1, 2020, the Regulation will be enforced through a new automatic process. Legislation passed in 2017, requires that the California Department of Motor Vehicles(DMV) check that vehicles are compliant with, or exempt from, the Regulation. If a vehicle is not compliant with the rule, DMV can no longer register that vehicle. The new DMV compliance verification process will better enforce the Regulation, protect public health and level the playing field for businesses throughout California.

When non-compliant vehicle owners receive their registration renewal notices from DMV, it will include a warning stating that the vehicle is CARB Non-Compliant. If the vehicle is not compliant, the vehicle owner may be able to pay the registration fee to receive a 90-day Temporary Operating Permit (TOP) from DMV. The 90-day period starts on the day the current vehicle registration expires. While the vehicle owner can drive during this period, the vehicle is still not compliant with CARB’s Truck & Bus Regulation and could still be cited. The TOP is not a compliance extension; CARB considers a TOP permit the final opportunity to either demonstrate or achieve compliance with the Truck & Bus Regulation.

The Truck and Bus Regulation is California law. CARB’s staff, management, executive officers, and board members are all bound by the requirements of the regulation and do not have the authority to offer any additional extensions or exceptions not already provided for in the law.

More Information ►
Frequently Asked Questions ►
Check Engine Compliance ►



Filter Information

DPF/soot filters (diesel particulate filter, VDECS, PM filter, exhaust retrofit)



Upcoming Deadlines

JANUARY 1, 2023
  • DMV automatic compliance verification continues. If a vehicle is not compliant with the Regulation, DMV can no longer register that vehicle.
  • Heavier vehicles (Greater than 26,000 lbs GVWR) with EMY 2009 or older need to be replaced or repowered to a 2010 or newer EMY.

Check Engine Compliance ►
Find out if or when your vehicle is subject to DMV registration denials or holds.


Regulation Timeline

Truck and Bus Regulation - Highlighted engine requirement timelines (other requirements exist) 2019: Lighter vehicles with 1999 or older EMY* must be replaced or repowered already.
Heavier vehicles with 1995 or older EMY* must be replaced or repowered as of 2016.

2020: DMV Compliance Verification Begins. 
Lighter vehicles with 2003 or older EMY* must be replaced or repowered.
Heavier vehicles with 1999 or older EMY* must be replaced or repowered. 

2021: Lighter vehicles with 2006 or older EMY* must be replaced or repowered. Heavier vehicles with 2004 or older EMY* must be replaced or repowered.

2022: Heavier vehicles with 2006 or older EMY* must be replaced or repowered.

2023: Lighter vehicles with 2009 or older EMY* must be replaced or repowered. Heavier vehicles with 2009 or older EMY* must be replaced or repowered. 

*This timeline applies to diesel buses and trucks unless you are using a compliance option and reporting in TRUCRS. This timeline follows a scheduel for Engine Model Year (EMY). The Vehicle Model Year usually runs one year ahead of Engine Model Year.

Lighter vehicles - 14,001 - 26,000 lbs GVWR. Heavier vehices - Greater than 26,000lbs GVWR.