*Published Friday, February 6, 2026*

The California Air Resources Board will hold a public workshop Feb. 27, from 8:30 a.m. to 3:30 p.m., to discuss potential standards for off-road new diesel engines in California, referred to as Tier 5 standards. The Tier 5 rulemaking aims to reduce oxides of nitrogen, or NOx, and particulate matter emissions from new off-road compression-ignition engines sold in California. During the workshop, CARB staff will discuss draft amendments to the new off-road diesel engine emissions standards, including changes to the on-board diagnostics, off-road in-use testing, or ORIUT, and Tier 5 elements-last discussed at its Oct. 8, 2024, workshop. The ORIUT and OBD portions of the workshop are technical in nature. [Register for the Zoom meeting](https://us06web.zoom.us/webinar/register/WN_5Cu0eoM-Qeq3o9k1TdbYBw?utm_medium=email&utm_source=govdelivery#/registration).

Staff contact: Steven Fenaroli, [sfenaroli@cfbf.com](mailto:sfenaroli@cfbf.com).

Tier 5 Workshop Planned for Late February

https://mura.cfbf.com/index.cfm/_api/json/v1/cfbv2/content/E391CF97-C6A5-4541-BBB098158D143D0A/relatedcontent

The California Air Resources Board will hold a public workshop Feb. 27 to discuss proposed Tier 5 standards for new off-road diesel engines. The rulemaking would further reduce oxides of nitrogen and particulate matter emissions and includes technical updates to on-board diagnostics and off-road in-use testing requirements.

Tier 5 Workshop Planned for Late February

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