By Arthur Foerster and Jamie Friedland

On January 12, 2018, the California Air Resources Board (CARB) will conduct a public workshop regarding CARB staff’s potential amendments to California’s heavy-duty vehicle (HDV) emission warranty requirements. According to CARB staff, the workshop will focus on potential changes to Title 13, California Code of Regulations, Section 2036, and specifically, amendments to required emission warranty periods and manufacturer-scheduled maintenance. CARB staff will present the workshop as a webcast (available here).


Under United States law, the federal Clean Air Act (CAA) generally preempts individual states from adopting their own emission standards. The Act, however, grants California the ability to seek authorization to set the state’s own more stringent standards. See 42 U.S.C. § 7543(b). Manufacturers generally prefer a single national standard and, as a practical matter, often follow CARB standards when they are stricter.

Under current CARB rules, the applicable warranty period for heavy-duty diesel vehicles and engines (i.e., class 4 through 8) is whichever of the following comes first: five years, 100,000 miles, or 3,000 operation hours. See 13 CCR § 2036(c)(4). CARB staff’s proposal would maintain the five-year limit, while eliminating hour limits and lengthening mileage limits. Specifically, the proposal would increase the mileage limits to the following:

  • 350,000 miles, for class 8 vehicles;
  • 150,000 miles for class 6 and 7 vehicles; and
  • 110,000 miles for class 4 and 5 vehicles.

Staff’s rationale is that the lengthened periods “better reflect the longevity and usage of modern vehicles, thus better ensuring that any defects that cause engines or vehicles to fail to conform to applicable requirements are repaired at no additional cost to the vehicle owner,” according to a December 12, 2017 CARB Workshop Notice at 2. Staff believes the current warranty period “is insufficient to ensure that emission performance will remain effective for a meaningful portion of the vehicle’s service life.” Id. at 3.

Along with extended warranty periods, CARB staff has proposed changes to scheduled maintenance provisions. These changes would preclude potential attempts to shorten the new, extended periods. Specifically, staff seeks to remove regulatory language that limits the warranty period to the first scheduled maintenance. See 13 CCR § 2036(d). Staff also seeks to revise minimum scheduled maintenance intervals such that the minimum replacement interval for a component would be set to the shortest interval designated by any manufacturer (or the useful life if no manufacturer is currently scheduling). See 12/12/2017 CARB Workshop Notice at 4.

CARB staff is also considering amending other warranty-related provisions. These changes may include extending coverage to any component that can trigger an on-board diagnostics (OBD) malfunction indicator light (MIL) and precluding the replacement of certain “high-cost and catastrophic emission failure-inducing components” during the vehicle’s useful life, unless paid for by the manufacturer. See id. Staff intends to present these proposed warranty amendments for Board consideration in May 2018.

A staged process to achieve a broader goal

CARB’s upcoming workshop is only the first step in the agency’s staged process for achieving its broader goal of reducing NOx emissions from heavy-duty vehicles and engines. CARB first introduced its current plan for reducing HDV NOx emissions at a public workshop in November 2016. The workshop included presentations on a number of topics, including reduction goals, warranty, low-load testing, and other related issues. In later workshops, CARB proposed a step process — first addressing warranty, then addressing useful life periods and other low-NOx control measures. See 12/12/2017 CARB Workshop Notice at 4.

CARB staff believes achieving lower NOx emissions from HDVs is necessary for attaining federal air quality standards, and amendments to warranty rules are part of that process. According to CARB’s website, other potential revisions include lowering the NOx standard, adopting a low-load test cycle, amending useful life and durability provisions, and amending the Not-to-Exceed (NTE) program. CARB is currently funding several research projects regarding the feasibility of lower NOx emissions. See id. The agency intends to take action on a lower NOx standard in 2019. See id.

Looking ahead

Latham has been and will continue to follow, California’s push toward HDV low-NOx emissions. See Are New On-Highway, Heavy-Duty Diesel NOx Standards Down the Road? (May 11, 2017). Stakeholders in the current efforts include a much larger group than traditional vehicle and engine manufacturers. As the current proposed rules now impact a much larger group of stakeholders, all affected entities — whatever their position — should monitor the developments, and participate in CARB’s public process.