The second half of 2020 sped by with all the fleetness of a supercharged truck. In case you missed it, Squire Patton Boggs has provided a recap of the Agency’s revised tampering policy as well as trends in the broader industry. Although we expect the new administration to lead to changes in approach to mobile source regulation, the tampering policy is likely to remain in place since it is an integral part of the Agency’s National Compliance Strategy on aftermarket defeat devices. In 2020, for example, the US EPA reported resolving 31 civil enforcement cases related to tampering and aftermarket defeat devices – “the most for any one year in the agency’s history.”

Looking to the future, several manufacturers in the industry are also planning for a post-diesel market. Recently, seven of the largest truck manufacturers in Europe announced that they would eliminate the use of diesel by 2040 – including, for one manufacturer, the intention to have carbon neutral manufacturing in its North American facilities by approximately 2025. As manufacturers plan for the future, an expected priority will be to push for unified regulatory standards at the state and federal level, especially as the California Air Resources Board (CARB) advances initiatives and rulemaking designed to reduce emissions from heavy-duty and off-road vehicles and engines.

US EPA Tampering Policy

In late November 2020, US EPA issued a new civil enforcement policy for violations of 42 USC § 7522(a)(3), § 7547(d), and 40 CFR § 1068.101(b)(1)-(2), which address the prohibitions against tampering with vehicle emission control systems and the sale/installation/use of aftermarket defeat devices. The purpose of the policy is to supersede and replace the long-time US EPA Mobile Source Enforcement Memo 1A from June 1974. Memo 1A was originally issued to provide guidance and clarity as to the Agency’s plans for enforcing the Clean Air Act tampering prohibition in the context of aftermarket parts.

The foundation of the original policy was that US EPA will exercise enforcement discretion for persons with a documented reasonable basis that the tampering action in question does not adversely affect emissions performance. This remains consistent in the new policy but with a more detailed description of how one can establish such a reasonable basis across six categories:

  • Identical to Certified Configuration;
  • Emissions Testing for Replacement After-Treatment Systems for Older Vehicles, Engines, and Equipment;
  • New After-Treatment Systems that Decrease Emissions;
  • Emissions Testing;
  • EPA Certification (conduct certified under 40 CFR Part 85, Subpart V); and
  • CARB Certification (Exemptions for emissions-related design elements).

US EPA qualifies the list is meant to be “illustrative and is not exhaustive.” For example, for a replacement part identical to the certified configuration, the Agency directs the part manufacturer should document that the replacement part will perform identically to the OEM part being replaced and have available either (1) documentation the replacement part is identical in all emission-related aspects (i.e., engineering drawings) or (2) test results supporting the representation.

The revised policy also provides more clarity on what it does not apply to, additional categories of vehicle and fuel types, and updated technology references. For example, the new policy addresses that modern vehicles and engines are equipped with electronic control units (ECUs) and tampering with such a control system, such as with the use of tuners, could constitute an illegal defeat device and/or tampering. Parts or components that also change onboard diagnostic (OBD) systems may fall into the category of an illegal defeat device, and a delete kit is provided as an example. However, the Agency explicitly clarifies in the revised policy that its enforcement discretion for documenting a reasonable basis “does not apply, however, to conduct affecting an OBD system, which may be subject to enforcement regardless of effect on emissions.”

While this policy can help provide a basis for aftermarket industry participants to reduce the risk of Agency enforcement, it should be cautioned that many states have their own regulatory systems addressing tampering and defeat devices. The policy cautions that it addresses only the federal Clean Air Act and “[m]any states also have laws prohibiting tampering with in-use vehicles, and some states also prohibit dealers from selling tampered in-use vehicles.” The policy does not affect compliance with such state and local laws, as applicable.

This revised policy is in line with the Agency’s recent focus on tampering initiatives as part of its National Compliance Initiative for aftermarket defeat devices. The Agency’s Air Enforcement Division completed and released a study entitled Tampered Diesel Pickup Trucks: A Review of Aggregated Evidence from EPA Civil Enforcement Investigations. The report is intended to inform both US EPA and state partners of the impact that tampering has and the results of numerous civil investigations. The report identifies that more than 550,000 diesel trucks have been tampered with in the last decade resulting in an estimated “more than 570,000 tons of excess oxides of nitrogen (NOx) and 5,000 tons of particulate matter (PM).”


On the state level, California Air Resources Board formally approved its Heavy-Duty Low NOx Omnibus rulemaking during a hearing on August 27, 2020. Squire Patton Boggs previously discussed the proposed rule in this article, and the requirements approved at the August meeting are consistent with the June 2020 proposal.

CARB also issued a draft Mobile Source Strategy in late November 2020. For on-road heavy duty vehicles, CARB highlighted the passage of the Omnibus rulemaking as well as its regulations on zero-emission trucks and buses. CARB explains that “[t]aken together, these requirements ensure lower NOx emissions over a more comprehensive range of vehicle operation.” For off-road vehicles and equipment, CARB identified a list of strategies it may consider to reduce air pollutants and GHG emissions in the sector. One example under consideration includes introduction of “more stringent emission standards such as Tier 5 to reduce emissions from new internal combustion engines, and OBD standards to ensure emissions from those engines” meet expectations through the engine’s useful life. Where feasible, CARB also intends to look for areas to implement zero-emission technologies in the off-road sector.

The opinions expressed are those of the author and do not necessarily reflect the views of the Firm, its clients, or any of its or their respective affiliates. This article is for general information purposes and is not intended to be and should not be taken as legal advice.