California is now actively banning older diesel trucks from operating on its roads.

A new rule states that any diesel vehicle weighing over 14,000 pounds with an engine built before the 2010 model year is banned from California roads effective January 1, 2023. The rule, part of a set of emissions regulations implemented by the California Air Resources Board (CARB) in 2008, affects around 200,000 trucks and buses, including 70,000 big rigs, according to SFGate.

Exceptions will be made for older vehicles that have their engines replaced with ones from after the 2010 model year, and for vehicles that travel fewer than 1,000 miles per year. In a recent memo, CARB said most fleet operators had already complied, with 1.58 million vehicles getting fitted with new post-2010 engines.

Mack Pinnacle series

Mack Pinnacle series

Enforcement for any outliers will take the form of California's DMV denying new registrations to non-compliant vehicles. CARB will also audit truck and bus fleets and issue fines where appropriate.

CARB said on its website that diesel exhaust is responsible for 70% of the cancer risk from airborne substances, but the vehicles that produce most of it have been subject to less stringent emissions rules than passenger cars.

For years, regulations for heavy trucks have lagged those for passenger vehicles, but they're starting to catch up. EPA regulations have been stepped up under the Biden administration, marking the first update in emissions standards for heavy-duty vehicles in more than 20 years, but they still fall short of those in California.

2014 Peterbilt 579

2014 Peterbilt 579

The Golden State wants to mandate electric commercial trucks by 2045. In the meantime, the state has tougher emissions standards for new vehicles that 17 other states have signed on to.

Those tougher standards were opposed by truckmakers until recently, and it's unclear how vehicle owners will react. As the EPA has pointed out, illegal emissions tampering on diesel pickups is also rampant. If that expands to larger commercial vehicles, it could undo some of the benefits of California's ban on older diesel powertrains.