“Freedom to Fix”: New Presidential Memorandum and EPA Guidance on Vehicle Tampering Add Little to Existing Framework

On June 29, 2026, President Trump issued a memorandum directing the Administrator of the U.S. Environmental Protection Agency (EPA) to clarify further within 30 days federal motor vehicle tampering enforcement policy.¹ The memorandum is styled as “Freedom to Fix” and is meant to reduce costs for individuals by facilitating the repair of one’s own vehicle with respect to federal Clean Air Act (CAA) requirements. The memorandum and subsequent EPA statements underscore EPA’s longstanding policy that individuals with a reasonable basis to conclude that repairs will not adversely affect emissions do not violate the federal tampering prohibition. For example, EPA explains that returning the vehicle to its certified configuration after a repair and relying on trade group-sponsored testing protocols for aftermarket parts may provide such a reasonable basis. Otherwise, we do not believe the memorandum or recent EPA statements to date alter such longstanding policy or break new ground.

The memorandum is part of a suite of actions taken by the administration to recalibrate federal regulatory enforcement related to motor vehicle tampering. In January 2026, the U.S. Department of Justice (DOJ) ordered federal prosecutors to drop criminal tampering charges brought under the CAA.² In February 2026, EPA issued guidance meant to affirm the “Right to Repair” engines used in the agricultural industry.³ That guidance clarified that it is lawful to take a non-road diesel engine out of certified configuration temporarily to effect a repair, so long as the engine is returned to certified configuration before returning to service.

The June 29 Presidential Memorandum instructs EPA to (1) issue guidance clarifying what actions individuals may take to repair their own vehicles’ emissions systems consistent with the Clean Air Act; (2) expedite testing of aftermarket parts for conformance with the CAA; and (3) consider deprioritizing civil tampering enforcement actions against individuals who attempt in good faith to fix their vehicles to the original configuration.

The memorandum criticizes California’s aftermarket parts certification process, calling it slow, faulty, and an unwarranted delegation of CAA compliance to the state. The memorandum directs EPA to create alternatives to the California process, though the California certification requirement applies and will continue to apply to parts sold in that state, and a federal aftermarket certification program already exists for light-duty vehicles.⁴

Federal tampering policy is nothing new, and EPA’s recent actions do not change the fundamental policy. Since 1974, EPA has taken the position that replacement or repair of an emissions-related component is not tampering when done with a “reasonable basis” for knowing that the action will not adversely affect emissions performance.⁵ That policy aimed to relieve uncertainty as to what repairs are lawful, and to facilitate the sale of aftermarket parts. During President Trump’s first term, in November 2020, EPA issued a new Tampering Policy superseding the 1974 policy and reiterating this “reasonable basis” enforcement approach, providing several examples of a documentable “reasonable basis” that can justify replacement or repair of an emissions-related component.⁶ The same November 2020 Tampering Policy states that EPA focuses enforcement efforts on companies and service shops, implying that enforcement against individuals fixing their own vehicles is not an enforcement priority.

So far, EPA’s implementation of the president’s recent directive has come in the form of a new July 1, 2026 guidance letter and a letter the same day approving a trade association’s aftermarket parts emissions testing program as satisfying the November 2020 Tampering Policy.⁷

The July 1, 2026 guidance letter largely echoes the February 2026 non-road engine guidance that repairs are lawful so long as the vehicle’s certified configuration is restored before the vehicle returns to service.⁸ The new guidance letter also discusses the regulatory provisions requiring vehicle manufacturers to post publicly certain information about emissions control systems. That information enables repair shops and manufacturers of aftermarket parts to facilitate repairs. The July 1 letter does not state explicitly that the agency will deprioritize tampering enforcement against individuals, and does not reference or appear to supersede the November 2020 Tampering Policy and its “reasonable basis” rule. Rather, it supplements one example of a documented “reasonable basis” provided by the November 2020 guidance: that a person has a reasonable basis for making a repair if the repair restores a vehicle to its certified or original configuration.

EPA also published a letter to Specialty Equipment Market Association (SEMA) approving that organization’s emissions testing program for aftermarket emissions components.⁹ SEMA had requested that EPA declare its testing program to be a reasonable basis for replacement or repair under the November 2020 Tampering Policy. That policy includes, as an example of a reasonable basis, that a repair is lawful where emissions testing of an aftermarket component shows compliance with emissions standards. The letter to SEMA states that aftermarket parts manufacturers and vendors may ordinarily rely on SEMA’s certification as documentation that a part does not adversely affect emissions, though EPA reserves the right to consider any potential violations on a case-by-case basis.

EPA’s letter to SEMA does not mention EPA’s own Voluntary Aftermarket Part Certification Program, which is codified in EPA regulations.¹⁰ Certification under that program is listed as an example of a reasonable basis in the November 2020 Tampering Policy. It is not clear why neither the June 2026 Presidential Memorandum nor EPA’s resulting guidance mentioned this federal program. The Presidential Memorandum overlooks the program’s existence in stating that “[t]he California Air Resources Board (CARB) has the only certification process for aftermarket parts currently recognized as sufficient under the CAA[.]” The federal program is limited to light-duty vehicles and trucks,¹¹ whereas the Tampering Policy reaches on-highway and nonroad engines more broadly. Still, EPA did not explain why it passed over its own regulatory program.

The Presidential Memorandum took aim at the California aftermarket parts certification program, calling it “faulty,” “costly,” and slow, and stating that “it effectively hands the determination of Federal compliance over to the State of California.” The Tampering Policy issued during President Trump’s first term includes certification of an aftermarket part through California’s process as one of several examples of a “reasonable basis” for repair. California does not require government approval for installation of replacement parts, i.e., parts functionally identical to original equipment.¹² A modified part (not functionally identical to the original) or an add-on part (not a replacement part or a modified part) can be installed only once approved by the California Air Resources Board.¹³ Approval requires the part manufacturer to show through testing or engineering analysis that the part will not cause the vehicle to exceed its certified emission standards and will not impair the function of the onboard diagnostics (OBD).¹⁴ Approval is only required for aftermarket parts sold, advertised, or installed in California. A spokesperson for the state has explained that this program has been in place for 50 years and takes an average of 90 days.¹⁵ California’s aftermarket parts approval process applies to in-use vehicles and is not preempted by the CAA. As such, the program remains applicable and enforceable in California. Other states and local jurisdictions across the country also have adopted anti-tampering laws. The November 2020 Tampering Policy acknowledges such laws as applicable and not preempted by any federal law, regulation, or policy.¹⁶

EPA’s recent updates also have not addressed the treatment of OBD systems. OBD systems report the status of a vehicle’s emissions control components. The November 2020 Tampering Policy explicitly carves out OBD repairs from the “reasonable basis” rule, stating that conduct affecting an OBD system may be subject to enforcement regardless of its effect on emissions.¹⁷ EPA’s position on OBD repair apparently remains the same, absent any statement by the agency that this position is revoked or superseded. Separately, however, the DOJ has dismissed criminal tampering charges related to OBD. President Trump also has recently pardoned some individuals convicted of OBD tampering.¹⁸

The Arnold & Porter team will continue monitoring these developments in federal motor vehicle tampering policy and will supplement this post if EPA issues additional guidance.

© Arnold & Porter Kaye Scholer LLP 2026 All Rights Reserved. This Blog post is intended to be a general summary of the law and does not constitute legal advice. You should consult with counsel to determine applicable legal requirements in a specific fact situation.