40 CFR § 1039.401 - General provisions.

---
identifier: "/us/cfr/t40/s1039.401"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 1039.401 - General provisions."
title_number: 40
title_name: "Protection of Environment"
section_number: "1039.401"
section_name: "General provisions."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "U"
subchapter_name: "AIR POLLUTION CONTROLS"
part_number: "1039"
part_name: "CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
regulatory_source: "69 FR 39213, June 29, 2004, unless otherwise noted."
cfr_part: "1039"
---


# 1039.401 General provisions.

We may perform in-use testing of any engine subject to the standards of this part. However, we will limit recall testing to the first 75 percent of each engine's useful life as specified in § 1039.101(g).