LIVONIA, Mich. — Roush CleanTech has received the Environmental Protection Agency’s and California Air Resources Board’s (CARB’s) heavy-duty onboard diagnostics certification (HD-OBD) for all of its engines, the propane fuel system manufacturer announced on Tuesday.

Roush explained that until 2018 model year, alternative-fuel vehicles had been exempt from this certification, but they are now held to the same requirements as gasoline vehicles.

“Vehicles powered by a fuel other than gasoline or diesel should no longer be considered alternative,” said Todd Mouw, president of Roush CleanTech. “As shown by the regulatory agencies’ decisions to require all fuels in its HD-OBD certification, propane autogas and others like compressed natural gas are moving into the mainstream.”

A Roush spokesperson said that the requirement is federal, so it affects all 50 states.

This HD-OBD certification applies to all vehicles over 14,000 pounds GVWR. The onboard monitors will now track and report out the continuing compliance of the emissions performance of the vehicle, as they have since 2016 for gasoline vehicles. Passenger cars and light-duty vehicles have come equipped with onboard diagnostic systems since the 1990s.

Roush CleanTech said that all vehicles powered by its propane autogas fuel systems with Ford 6.8L 2V and 3V engines, including medium-duty fleet vehicles and school buses, are covered under the CARB HD-OBD certification. The 3V engine is also certified to the optional low nitrogen oxide level of 0.05 g/bhp-hr.