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Sinister Diesel to pay $1M in fines

Jun 21, 2023

A Roseville-based truck parts manufacturer on Tuesday agreed to pay $1 million after pleading guilty in Sacramento federal court to conspiracy and for making and selling illegal “defeat devices” that sidestep emission controls, a U.S. Attorney said.

Representatives for the company, diesel performance parts maker Sinister Mfg. Company Inc. — doing business as “Sinister Diesel” — pleaded guilty to the criminal charges and agreed to pay the criminal fines and civil penalties.

The company, which has offices at 2025 Opportunity Drive in Roseville, also agreed to carry out a compliance program and to not manufacture, sell or install any device that defeats a vehicle’s emissions controls, Phillip A. Talbert, the U.S. Attorney for the Eastern District of California, stated in a press release.

Sinister Diesel pleaded guilty to a two-count Information, charging it with conspiracy to violate the Clean Air Act (CAA) and defraud the United States, and with violating the CAA by tampering with the device that monitors the emissions control system of a diesel truck. Under the plea agreement, Sinister Diesel agreed to pay a $500,000 criminal fine, Talbert noted.

Sinister also must pay $500,000 under the civil consent decree, which the United States filed at the same time as the civil complaint against Sinister Diesel, alleging violations of the CAA’s ban against the sale or manufacture of devices that bypass, defeat or disable emissions controls. The civil consent decree bars the company from making, selling or offering to sell defeat products, among them delete tuners, and prevents Sinister Diesel from transferring intellectual property that would allow others to make such products.

To ensure compliance with these requirements, Sinister Diesel will carry out “a robust internal training program and notify its distributors and former customers about the settlement,” Talbert stated.

“Sinister Diesel sold products that allowed drivers to strip the emissions controls from their trucks, causing a dramatic increase in the release of pollutants that worsen air quality and harm the quality of life,” he added. “Environmental laws that control diesel pollution are especially important to protect sensitive populations such as the young, the elderly, and people who suffer from respiratory conditions.  My Office will continue to vigorously prosecute those who place profit above the public’s health and the environment.”

Talbert stated diesel emissions contain multiple hazardous compounds and harm human health and the environment. Such emissions have been found to cause and worsen respiratory ailments such as asthma and lung cancer. One study found that 21,000 American deaths annually are attributable to diesel particulate matter. Additionally, exposure to polluted air in utero has been associated with a host of problems with lifelong ramifications, including low birth weight, preterm birth, autism, asthma and brain and memory disorders.

Talbert’s prepared statement came with a photo of a diesel truck “rolling coal” that Sinister Diesel posted to its Facebook page titled: “Get Serious. Get Sinister.” Rolling coal occurs when a modified diesel engine spews large amounts of black or gray exhaust fumes, diesel fuel that has not been completely burned by the engine.

“Businesses that manufacture and sell illegal devices to defeat a vehicle’s emissions controls foster pollution and risk decades of progress in curtailing harmful emissions from motor vehicles in this country,” said Assistant Attorney General Todd Kim of the U.S. Justice Department’s Environment and Natural Resources Division. “The plea agreement and civil settlement show that we will take strong action to enforce the Clean Air Act and ensure that emissions control requirements for cars and trucks are being followed.”

“For close to 10 years, Sinister Diesel sold parts designed to override or disable the emissions control systems on trucks,” said Principal Deputy Assistant Administrator Larry Starfield for the Environmental Protection Agency’s Office of Enforcement and Compliance Assurance. “EPA testing has shown that a vehicle altered with these parts can emit more than 100 times the amount of certain harmful air pollutants, compared to a vehicle with an intact emissions control system.”

According to court documents, Sinister Diesel — from its 2010 incorporation to April 2020 — manufactured and sold parts intended to be installed on motor vehicles, particularly diesel trucks, to enable “deleting” the trucks by removing or disabling the trucks’ emissions control systems. Various products, referred to as “delete devices” or “defeat devices,” are used in the process of “deleting” a vehicle. Sinister often sold its products as part of “delete kits,” sometimes bundled with “delete tunes.” The delete tunes were software produced by another company which could alter a diesel truck’s onboard computer to allow a truck with its emissions controls “deleted” to appear to run normally.

At the company’s website,, was a “Race Parts Notice,” followed by by “Attn: Customers, Shops, Retailers, WDs,” indicating that, effective April 30, 2020, the company would “no longer offer any EGR or DPF delete race products.”

The notice also indicated that the EPA “… will not stop until all emission defeating devices and race parts are eliminated from the market,” and ended the notice, writing, “Inventory is limited on race products and will not be replenished once depleted.”

Employees at three diesel truck stores in Fairfield — ProSource Diesel, North Bay Truck Center and NAPA Auto Parts — said their businesses no longer sell Sinister Diesel products.

Additionally, through its employees, noted Talbert, Sinister Diesel reached agreements with other companies that manufactured tuners or tuning platforms to sell their products bundled together. Sinister would often advise customers on other needed parts for their deleted vehicles to run properly with Sinister’s delete kits — such as a tuner or tuning platform and delete tunes — and sell them those products, too. Sinister also counseled customers on how to evade state emissions tests.

Though Sinister sometimes labeled its delete products for “racing” and included disclaimers in marketing materials indicating that its products should be used only in off-road settings, the company knew most of its delete products were purchased by diesel truck drivers who used those products on public roads, not racetracks. At times, approximately 25% of Sinister’s gross revenue stemmed from its delete products. According to Sinister’s sales statistics, between Oct. 30, 2015, and July 17, 2017, it sold 39,792 defeat devices, including at least 35,960 kits that disable vehicles’ exhaust gas recirculation systems.

Deleting a diesel truck causes its emissions to increase dramatically. For example, for a fully deleted truck with all emissions equipment removed, EPA testing has quantified the increased emissions as follows: Nitrogen oxides increased 310 times, nonmethane hydrocarbons increased 1,400 times, carbon monoxide increased 120 times and particulate matter increased 40 times. EPA’s Air Enforcement Division released a report in November 2020 finding that more than 500,000 diesel pickup trucks in the United States — approximately 15% of U.S. diesel trucks that were originally certified with emissions controls — have been illegally deleted.

Sinister Diesel representatives are scheduled to be sentenced in the criminal case by U.S. District Court Judge John A. Mendez on Nov. 14.

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