The California Air Resource Board Proposes Changes To Omnibus Low NOx Rule

On Aug. 1, 2023, the California Air Resources Board published and requested comments on proposed changes to the Heavy-Duty Engine and Vehicle Omnibus regulation. The deadline for submitting comments is September 18, 2023. A public hearing may be held if requested.

Last September, the California Air Resources Board adopted the Omnibus regulation which established more stringent NOx and particulate matter standards applicable to new 2024 and later Model Year medium- and heavy-duty diesel engines. Warranty and useful life periods were also lengthened. Then, on Jan. 24, 2023, the US EPA finalized similar, but different requirements (in its Clean Trucks Plan NOx rule). EPA’s rule sets new NOx and other standards beginning with MY2027. The California Air Resources Board’s 2031 and later standards and test procedures are more stringent than EPA’s, as are its 2024-26 Omnibus requirements.

Since finalizing its regulation last year, the California Air Resources Board has heard from the industry that its rule would result in certain vehicle buyers being left without products given manufacturers’ inability to meet the standards in the 2024-2026 timeframe. Thus, the California Air Resources Board is now proposing to amend the rule to provide manufacturers the opportunity to produce and certify greater numbers of 2024-2026 legacy engines. This opportunity will allow manufacturers to sell less costly, higher NOx engines. Savings are projected to range from $1993 to $4565 per engine (depending on vehicle size). However, manufacturers electing to produce legacy engines will be required to offset the excess emissions. They can use credits from heavy duty-zero emission engine averaging set; they can use credits from the same heavy-duty diesel engine averaging set; and they can use emission reductions gained from projects in disadvantaged communities. All three offset options will cost the manufacturer money and the net saving to the manufacturer is projected to be zero.

Since legacy diesel engines use less diesel exhaust fluid than compliant engines, vehicle owners would save money in diesel exhaust fluid ($61 to $204 a year depending on vehicle class). However, the California Air Resources Board believes that the net savings to truck buyers will be zero because they anticipate legacy vehicles selling at a premium price.

The RV Industry Association is planning to work with interested members to submit comments to the California Air Resources Board on these proposed changes prior to the mid-September deadline.