Core Summary

  • The U.S. Environmental Protection Agency (EPA) is seeking to revise parts of its 2023 heavy-duty diesel truck nitrogen oxide (NOx) emission regulations, including eliminating diesel exhaust fluid (DEF)-related engine derating and speed limiting for new trucks, according toa July 9 press release。
  • Theproposalwould also reduce emission warranty requirements, delay the implementation of certain regulatory useful life provisions, and establish temporary nonconformance penalties for some heavy-duty diesel engines that cannot meet the new NOx standards.
  • If finalized, the EPA estimates the new rule would save truck drivers $12 billion and reduce the cost of each new truck by up to $6,000.

In-Depth Analysis

The proposal focuses on a major pain point in the trucking industry's daily maintenance: engine derating caused by DEF.

Under current regulations, when a truck has an emission system malfunction, it can be programmed to reduce engine power or limit speed until repairs are completed. Fleet operators have long argued thatsensor failures and other DEF-related issuescan force otherwise operational trucks off the road, resulting in costly downtime.

Under the EPA's proposal, new trucks would no longer be required to derate due to emission system malfunctions. Instead, drivers would receive warning notifications, allowing them to continue operating the vehicle until repairs are completed.

The agency also proposes giving manufacturers more time to develop and test new technologies before the relevant requirements in the 2023 rule take effect, but without providing additional specific timeline details.

"If finalized, these changes will help manufacturers continue to improve their vehicles without being forced to rush immature products to market," EPA Administrator Lee Zeldin said in the press release.

The proposed rule will undergo a 45-day public comment period and a public hearing, after which the EPA will decide whether to finalize the changes.

This announcement follows the EPA's recent release of the"Freedom to Fix" guidance. That guidance clarifies that truck owners and independent repair shops can repair emission control systems and restore vehicles to their certified configuration without violating federal anti-tampering rules. The agency also directed manufacturers to improve access to emission-related diagnostic information, software, and tools to expand repair options.