EPA Proposes to End DEF Derates on Nonroad Equipment

*By Telescro Editorial Team*

The US Environmental Protection Agency has proposed replacing mandatory engine derates on SCR-equipped diesel machines with warning lights and alarms, and the window to comment closes at 11:59 PM EDT on Saturday, 29 August 2026. The proposal was announced on 9 July 2026 and published in the Federal Register on 14 July 2026 under Docket ID No. EPA-HQ-OAR-2026-0728. Most coverage has framed it as a trucking story, but EPA’s own rule summary states the inducement change would apply to nonroad engines and equipment as well, which puts telehandlers inside the scope.

## What Changed

Nothing has changed yet: this is a proposal, not a final rule. EPA’s January 2023 final rule revised inducements for heavy-duty highway engines, not nonroad diesel engines. Nonroad equipment remains subject to its applicable existing requirements and guidance unless and until changes are finalized.

EPA proposes to amend the inducement provisions for selective catalytic reduction systems that use diesel exhaust fluid. The Federal Register notice states that EPA is proposing to replace engine performance derates for SCR-related inducements with visible and/or audible notifications, and that these new inducement provisions would apply to new heavy-duty highway engines as well as new light-duty and medium-duty vehicles and nonroad diesel engines.

The scope split matters more than the headline. The derate replacement is written for newly manufactured equipment; for machines already in service, the notice says only that EPA is considering new inducement guidance for in-use highway and nonroad diesel engines, vehicles and equipment. The SBA Office of Advocacy summarised the same element on 15 July 2026 in the same terms, and EPA’s rule summary adds that it is considering a process to issue updated guidance that would allow manufacturers to modify in-use engines and vehicles.

The rest of the package is highway-only and should not be read across to your telehandler fleet. EPA proposes changes to the regulatory useful life periods and the emission-related warranty periods for model year 2027 and later heavy-duty highway engines, and proposes to make nonconformance penalties available to manufacturers of medium heavy-duty and heavy heavy-duty engines beginning in model year 2027.

## Key Numbers

The notice states that comments must be received on or before 29 August 2026, and EPA’s hearing page sets the written cut-off at 11:59 PM EDT that Saturday, submitted to Docket ID No. EPA-HQ-OAR-2026-0728. The public hearing has concluded; EPA held virtual hearings on 29 July 2026 starting at 9:00 a.m. Eastern and on 30 July 2026 starting at 10:00 a.m. Eastern.

The notice appeared at 91 FR 43154 in Volume 91, No. 133, dated Tuesday 14 July 2026, under RIN 2060-AW83 and 40 CFR Parts 86, 1036, 1037, 1039, 1065 and 1071. Three supporting documents sit on the docket alongside it, and their identifiers are worth quoting if you file a comment: the Draft Regulatory Impact Analysis dated July 2026 (EPA-420-D-26-002), the Draft Technical Support Document on nonconformance penalties dated June 2026 (EPA-420-D-26-003), and the fact sheet EPA-420-F-26-012, issued July 2026.

## What It Means for Equipment Buyers

If you run Tier 4 Final telehandlers in the United States, the operational question is whether a DEF quality fault or sensor failure drops the machine into limp mode mid-shift or simply lights up the dash. Under the proposal that answer would differ by channel, so treat these as three separate procurement questions rather than one.

| Sourcing channel | What the proposal does | What to verify before you sign |
|—|—|—|
| New nonroad SCR-equipped machines (proposed: no later than MY2029) | Derate replaced by visible or audible notification, written into the proposed text | Ask for the docket citation in writing, not a verbal assurance |
| Machines already in your fleet | Nothing today; EPA says only that it is considering in-use guidance | Ask what authority any derate-disabling service offer relies on |
| Imported machines | Not addressed; the documents reviewed do not change certification | Match the engine family on the machine label to the manufacturer certificate |

For newly manufactured machines, the derate replacement is the part EPA has actually written into the proposed text. If it is finalised in its proposed form, machines certified after the effective date would use notifications instead of speed and power reductions. Until a final rule publishes, any dealer statement that a 2027 machine will not derate is a forecast, not a specification, and you should ask for it in writing against a docket citation.

For your existing fleet, nothing in the proposal changes machine behaviour today. EPA has framed in-use modification as guidance it is considering, which typically means a separate process on a later timetable. If a service provider offers to disable derate logic on an in-use engine now, that offer sits outside this proposal, and you should ask what authority they are relying on before agreeing to it.

For imported machines, the proposal as summarised by EPA addresses inducement behaviour, not certification. The documents reviewed here contain nothing that changes how an engine family is certified or how a machine is declared at the border, so treat your existing clearance checklist as unaffected until a final rule says otherwise. Buyers sourcing outside established North American dealer networks should still verify the engine family shown on the machine emission label against the certificate held by the manufacturer rather than relying on a spec sheet.

## Telescro Analysis

This suggests the practical value of the proposal for equipment owners is uptime risk rather than purchase price. A derate event costs a shift, a service call and sometimes a rental replacement, and moving that failure mode to a warning changes how a DEF fault propagates through a job schedule. EPA has not published an equipment-level cost estimate for the nonroad portion in the material reviewed here, so treat any quantified saving as unsupported until the Draft Regulatory Impact Analysis is read in full.

For buyers writing multi-unit RFQs into the 2027 model year, the useful life and emission warranty changes are the item to watch, and the item most likely to be misapplied. Those changes are proposed for heavy-duty highway engines. If a supplier cites them in a telehandler warranty discussion, ask which CFR part they are relying on.

The comment window itself is the near-term action. Fleet owners, rental companies and importers can file to the docket until 29 August 2026, and a comment describing a specific derate incident on a specific machine class carries more weight in a rulemaking record than a general position statement.

## Risks or Limitations

This is a proposal. EPA can finalise it as written, modify it, or decline to finalise it, and no date for a final rule appears in the material reviewed here.

Emission limits are not on the table. A footnote in the preamble states that while the proposed rule includes a range of specific, targeted amendments, EPA is otherwise not reopening those provisions and is neither proposing nor seeking comment on the underlying standards or program requirements. Read that as confirmation that Tier 4 Final limits themselves are unchanged by this docket.

This article draws on the notice summary, the DATES section and the inducement passage of the preamble, not on the full regulatory text. If your purchase decision turns on exact scope or on the proposed regulatory language, read the notice on the docket rather than any summary, including this one.

State-level requirements are not addressed here. California administers its own nonroad programme, and a federal change to inducement logic does not automatically flow through to state rules.

## Sources

– [US EPA — Proposed Rule: Amendments and Nonconformance Penalties for Model Year 2027 and Later Heavy-Duty Highway Engines](https://www.epa.gov/regulations-emissions-vehicles-and-engines/proposed-rule-amendments-and-nonconformance-penalties)
– [US EPA — Public Hearing and Public Comments, Docket EPA-HQ-OAR-2026-0728](https://www.epa.gov/regulations-emissions-vehicles-and-engines/public-hearing-and-public-comments-amendments-and)
– [SBA Office of Advocacy — EPA Proposes to Revise Heavy Duty Engine Rules and End DEF Deratements](https://advocacy.sba.gov/2026/07/15/epa-proposes-to-revise-heavy-duty-engine-rules-and-end-def-deratements/)
– [Federal Register — Notice of Proposed Rule, 91 FR 43154, 14 July 2026](https://www.govinfo.gov/content/pkg/FR-2026-07-14/pdf/2026-14112.pdf)