Two companies admit to tampering with emission monitoring systems

April 18, 2022

Land Line Staff


Two truck repair companies have pleaded guilty to conspiring with a Colorado diesel shop to tamper with emission monitoring systems on Class 8 trucks.

The U.S. Attorney’s Office for the District of Colorado issued a statement on the plea agreement.

The trucking repair companies involved:

  • Pro Diesel Inc., Des Moines, Iowa, an after-market supplier of remanufactured electronic fuel injectors and pumps for diesel engines.
  • Endrizzi Diesel LLC, Bolivar, Mo.

According to the plea agreements:

  • From July 2017 through May 2020, Pro Diesel Inc. paid a Colorado diesel shop identified as “E.D.” more than $76,000 to disable on-board diagnostic systems on 34 Class 8 trucks.
  • From January 2017 through December 2020, Endrizzi Diesel paid the same Colorado diesel shop more than $149,000 to disable the diagnostic systems on about 60 Class 8 trucks.

Both diesel repair companies pleaded guilty to one count of violating Title 18, United States Code, Section 371, the U.S. Attorney’s Office reported.

On-board diagnostics systems are under the Clean Air Act to be installed on vehicles to monitor emission control systems and to ensure they are functioning properly.

Tampering with emission monitoring systems is frequently referred to as “tuning,” according to the U.S. Attorney’s Office statement. One purpose for tuning an emission monitoring system is to allow the vehicles to continue to seemingly operate normally while the emission control system is disabled. This reduces the high costs associated with maintaining or repairing components of the emissions control systems on heavy-duty diesel trucks.

Tampered vehicles emit substantially more pollutants, such as nitrogen oxides, carbon monoxide, nonmethane hydrocarbons and particulate matter into the air.

Through a remote connection, individuals at the Colorado repair shop would run software programs to reprogram or “tune” the vehicle’s on-board diagnostic systems, prosecutors said in the statement. These programs would disable the monitoring functions of the diagnostics systems so they would no longer detect malfunctions in the emission control systems.

Sentencing is scheduled June 14 for Pro Diesel and June 29 for Endrizzi. LL

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