California Air Resources Board

The California Air Resources Board (CARB) has reached a settlement that resolves a civil enforcement case against diesel engine manufacturer, Volvo Group North America, LLC (Volvo). The settlement, announced on May 18, 2026, resolves alleged violations of California’s emission and certification laws. These violations involve over 10,000 model year 2010-2016 diesel engines manufactured by Volvo and installed in heavy-duty trucks operated in California. The settlement terms and conditions can be found in the administrative Settlement Agreement CARB developed this Frequently Asked Questions document to answer common questions related to this settlement and related recall repair.[1] 

What did Volvo do?

During review of Volvo’s certification applications, CARB found inconsistencies in the data and uncovered alleged violations of California’s emissions regulations. CARB alleged that Volvo failed to fully disclose certain emission controls called Auxiliary Emission Control Devices (AECDs) in approximately 10,000 of its model year 2010-2016 diesel engines in California. This failure produced additional smog-forming pollutants in excess of what is allowed by state law.

What role did CARB play in detecting these emission violations?

CARB analyzed Volvo’s certification documentation and emission test data to uncover the full extent of these AECDs. During the course of its investigation, the agency’s engineers determined the full functionality of these AECDs during operation of the subject engines.

What engines are included in the settlement?

Volvo’s model year 2010 through 2016 on-road, heavy-duty diesel engines.  Appendix E of the Settlement Agreement contains a list of effected engines in California.

What is included in the settlement?

Volvo will pay $196.5 million, which includes a civil penalty, reimbursement of costs, a mitigation payment, and the funding of several emissions-reduction projects. In addition, Volvo will do an engine recall (“repair”) and on-board diagnostic testing. There are also penalties if Volvo fails to comply with certain provisions of the Settlement Agreement.

Is there a repair for the violations?

Yes. Volvo is currently developing a software repair for the AECD issues affecting heavy-duty trucks equipped with the model year 2014-2016 Volvo diesel engines listed in Appendix E of the Settlement Agreement (excluding 16-liter engines). Volvo will submit the recall application to CARB for approval in the future and once approved, will notify owners of impacted heavy-duty vehicles.  

Why isn’t the repair ready now?

The repair is pending due to the complexity of the software development process. Each variation of the software requires additional calibration, testing, and verification to ensure optimal performance and stability. These steps are critical to avoid creating additional issues that would add significant time to the overall effort and frustration for owners.

What can/should an owner do if they own a vehicle with one of these model year 2014-2016 engines?

Owners of a heavy-duty truck equipped with a model year 2014-2016 Volvo diesel engine listed above (excluding 16-liter engines) should wait to receive a letter notifying them of the recall, which is expected to take place in 2027. This recall is not mandatory. At their option, truck owners can schedule an appointment to have their trucks repaired. Once Volvo repairs the truck, Volvo will provide the truck owner with an extended warranty for specific parts of the emission control system. The extended warranty also carries over to subsequent owners whose trucks had already received the recall software.

Do I have to get the repair to pass Clean Truck Check compliance or to register my vehicle?

No. As mentioned above, the recall is not mandatory.

Should I complete the repair before my required Clean Truck Check compliance deadline?

To avoid delays or test failures, complete the software repair well in advance of your Clean Truck Check (CTC) compliance deadline and allow enough vehicle operation to ensure the OBD system is fully ready before testing.

After a software repair, the vehicle needs sufficient time and operation to complete the OBD system self‑checks. Vehicles must demonstrate that required OBD monitors have completed their diagnostics and are in a “ready” state. This means the OBD system has operated long enough to determine the presence or absence of a diagnostic trouble code. Following a software repair or reset, it may take additional driving time for the system to return to a fully ready condition.

More information about CTC OBD readiness requirements.

Additional FAQs to get your vehicle ready for a CTC OBD test.

Do I need to pay for the repair?

No. There will be no charge to eligible truck owners or lessees for the repairs approved by CARB. Owners and lessees also do not have to release any right, including their right to sue the company to get the repair.

Will the repair affect my warranty?

Existing warranties remain in effect regardless of whether owners/lessees get the repair or not. Any vehicle that receives the repair will get an extended warranty that covers labor and certain parts that may be impacted by the repair, unless the vehicle has been modified with an aftermarket part, component or software.

If any component listed on the extended warranty is already causing the Malfunction Indicator Light (MIL) or “Check Engine” light to turn on, you may be denied extended warranty coverage on that part unless you fix it before bringing your truck in for the repair.

For more information on what is covered by the extended warranty, see Appendix F to the Settlement Agreement, or contact Volvo. If the company refuses to honor an owner/lessees regular or extended warranty, as applicable, please report it to CARB by emailing volvosettlement@arb.ca.gov

My MIL ("Check Engine" light) came on after the repair. Do I have to pay for the subsequent diagnostic check(s) by the dealer?

No. Diagnostic checks performed by your dealer after the repair are covered free of charge by the extended warranty.

[1] This FAQ document does not have the force of law, does not establish regulatory requirements, and is not legal advice. It does not supplant, replace, or amend the requirements in the administrative settlement agreement, nor does it contain all requirements in the settlement agreement. For more information, please see the settlement agreement on CARB’s website.