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Tier 5 Diesel Engine

Public Workgroup Meeting on December 14, 2022, to Discuss the Off-Road New Diesel Engine Tier 5 Rulemaking: Concepts for Averaging, Banking, and Trading, Idle Reduction, and On-Board Diagnostics.

The California Air Resources Board (CARB) staff invites you to participate remotely in a public workgroup meeting on December 14, 2022, 8:30 AM – 5:00 PM to discuss possible concepts and strategies to reduce oxides of nitrogen (NOx) and particulate matter (PM) emissions from new, off-road compression-ignition (CI) engines.

During the workgroup meeting, CARB staff will discuss concepts for the off-road new diesel engine Tier 5 rulemaking including a California-specific Averaging, Banking, and Trading (ABT) program, idle reduction, and On-Board Diagnostics (OBD).

The current ABT program is administered federally and allows engine manufacturers flexibility in complying with the standards by averaging emission levels across power categories and product lines nationwide. Significantly more stringent off-road diesel standards in California could result in excessive credit usage in California, potentially delaying the introduction of engines meeting Tier 5 standards indefinitely. To prevent this, California is considering adopting statewide averaging requirements to ensure that credits are used equitably within California and that Tier 5 compliant engines enter the California market in a timely manner.

CARB staff will also discuss concepts for reducing emission from off-road diesel engine idling. Currently, although California’s In-Use Off-Road Diesel-Fueled Fleets Regulation contains a 5-minute idle restriction and a requirement for affected fleets to have a written idle policy, that regulation does not apply to all diesel engines nor to all idling, and California’s new engine standards do not include idling restrictions. Prolonged idling can adversely affect exhaust temperature and Selective Catalytic Reduction (SCR) function resulting in higher NOx emissions. Off-road diesel engines can operate at idle for up to 50 percent of the time. The potential idle reduction concepts include requiring use of idle control systems such as auto shutdown or introducing an idling standard.

OBD is  currently not required for off-road engines. Many OBD features from existing on-road heavy-duty diesel engines could be applied to off-road engines. Staff will introduce some potential OBD concepts for off-road diesel engines.

The workgroup meeting will be held via Zoom webinar at the following date and time:

Date:                 December 14, 2022Time:                 8:30 a.m. – 5:00 p.m. PSTLocation:           Zoom Webinar/Teleconference