Diesel emissions systems on work trucks in the United States: what the Clean Air Act and EPA say about removal

This page reports what the official source says. It is not legal advice: ask the office named here. It quotes or restates the statute, the EPA's engine rules and an EPA enforcement page. It does not describe how any emission part works or how to service one.

The statute

Section 203 of the Clean Air Act is 42 U.S. Code section 7522, headed prohibited acts. Its paragraph (a)(3) has two parts that matter to a truck owner or a repair shop.

Part (A) makes it a prohibited act for any person to remove or render inoperative a device or element of design installed on a vehicle or engine in compliance with the regulations. Before sale to the ultimate purchaser, that covers any person. After the sale, the word "knowingly" applies.
Part (B) covers parts. It prohibits manufacturing, selling, offering to sell or installing a part or component where a principal effect is to bypass, defeat or render inoperative such a device, and where the person knows or should know of that use.

The statute then writes in exceptions. An action is not a prohibited act if it is done for the purpose of repair or replacement of the device, or is a necessary and temporary procedure to repair or replace another item, as long as the device is replaced afterward and works properly. A second exception covers conversion of a vehicle to a clean alternative fuel, where the vehicle meets the standard on that fuel and the device is put back and works on conventional fuel. The statute also says paragraph (3) does not require the use of manufacturer parts for maintenance or repair. See 42 U.S. Code 7522 as published by Cornell Law School.

The EPA's engine rules

Title 40 of the Code of Federal Regulations, part 1068, repeats the prohibition for engines and equipment. Section 1068.101(b)(1) is headed tampering. It says a person may not remove or render inoperative a device or element of design installed in compliance with the regulations, and may not knowingly do so after sale. It gives two examples of what counts: operating an engine without a supply of appropriate quality urea when the emission control system depends on urea to reduce nitrogen oxides, and using incorrect fuel or engine oil that renders the system inoperative. Section 1068.101(b)(2) is headed defeat devices and bars knowingly manufacturing, selling, offering to sell or installing a component that bypasses, impairs, defeats or disables emission control. The exceptions listed under tampering track the statute: repair with restoration to proper function, and a temporary emergency modification restored as quickly as possible. See eCFR 40 CFR 1068.101 on general prohibitions.

Section 1068.1 says who the part applies to. It says part 1068 applies to everyone, and names owners, operators, parts manufacturers and persons performing maintenance. It lists categories that include heavy-duty motor vehicles and engines regulated under 40 CFR parts 1036 and 1037, including trailers, and land-based nonroad compression-ignition engines regulated under part 1039. See eCFR 40 CFR 1068.1 on who the part applies to.

What the EPA says about enforcement

The EPA's page on vehicle and engine enforcement case resolutions says the Clean Air Act requires new engines and equipment sold in the United States to be certified to EPA emission requirements, and that the Act and its regulations also contain requirements on tampering, defeat devices, and vehicle and engine maintenance and alterations. It says the EPA may seek civil penalties or injunctive relief, including remediation and projects to offset excess emissions, in federal district court or through an administrative process, and that enforcement actions reach manufacturers, importers, distributors and consultants. The page states these civil penalty ceilings:

Violation	Civil penalty up to, as the EPA page states it
Per noncompliant vehicle or engine	US$45,268
Per tampering event or sale of a defeat device	US$4,527
Per day for reporting and recordkeeping violations	US$45,268

The page cites 42 U.S. Code 7524 and 40 CFR 19.4 for these figures. It also says the EPA often uses its Mobile Source Civil Penalty Policy to set a penalty in settlements. See the EPA vehicle and engine enforcement case resolutions page.

At a glance

Item	What the sources say
Statute	42 U.S. Code 7522(a)(3), removal or rendering inoperative, and defeat parts
Regulation	40 CFR 1068.101(b)(1) tampering and (b)(2) defeat devices
Who the regulation applies to	Everyone, including owners, operators, parts manufacturers and persons performing maintenance (1068.1)
Written-in exceptions	Repair or replacement with the device restored; temporary emergency modification restored; conversion to a clean alternative fuel
Penalty ceiling per tampering event	US$4,527, as the EPA page states it