# 40 C.F.R. § 1039.601 (2026): What compliance provisions apply? > Federal · Regulations · In force URL: https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_601 ## Section - **Citation:** 40 C.F.R. § 1039.601 (2026) - **Heading:** What compliance provisions apply? - **Jurisdiction:** Federal - **Kind:** Regulations - **Status:** In force - **Text as of:** August 14, 2026 - **Source:** Compiled text - **Location:** Title 40 CFR: Protection of Environment / Chapter I / Part 1039 / Subpart G / § 1039.601: § 1039.601 What compliance provisions apply? ## Text (a) Engine and equipment manufacturers, as well as owners, operators, and rebuilders of engines subject to the requirements of this part, and all other persons, must observe the provisions of this part, the requirements and prohibitions in 40 CFR part 1068, and the provisions of the Act. (b) Subpart C of this part describes how to test and certify dual-fuel and flexible-fuel engines. Some multi-fuel engines may not fit either of those defined terms. For such engines, we will determine whether it is most appropriate to treat them as single-fuel engines, dual-fuel engines, or flexible-fuel engines based on the range of possible and expected fuel mixtures. For example, an engine might burn natural gas but initiate combustion with a pilot injection of diesel fuel. If the engine is designed to operate with a single fueling algorithm ( i.e. , fueling rates are fixed at a given engine speed and load condition), we would generally treat it as a single-fuel engine. In this context, the combination of diesel fuel and natural gas would be its own fuel type. If the engine is designed to also operate on diesel fuel alone, we would generally treat it as a dual-fuel engine. If the engine is designed to operate on varying mixtures of the two fuels, we would generally treat it as a flexible-fuel engine. To the extent that requirements vary for the different fuels or fuel mixtures, we may apply the more stringent requirements. [81 FR 74137, Oct. 25, 2016, as amended at 86 FR 34505, June 29, 2021] ## Nearby sections - [40 C.F.R. § 1039.601 (2026) § 1039.601 What compliance provisions apply?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_601.md) - [40 C.F.R. § 1039.605 (2026) § 1039.605 What provisions apply to engines certified under the motor-vehicle program?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_605.md) - [40 C.F.R. § 1039.610 (2026) § 1039.610 What provisions apply to vehicles certified under the motor-vehicle program?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_610.md) - [40 C.F.R. § 1039.615 (2026) § 1039.615 What special provisions apply to engines using noncommercial fuels?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_615.md) - [40 C.F.R. § 1039.620 (2026) § 1039.620 What are the provisions for exempting engines used solely for competition?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_620.md) - [40 C.F.R. § 1039.625 (2026) § 1039.625 What requirements apply under the program for equipment-manufacturer flexibility?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_625.md) - [40 C.F.R. § 1039.626 (2026) § 1039.626 What special provisions apply to equipment imported under the equipment-manufacturer flexibility program?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_626.md) - [40 C.F.R. § 1039.627 (2026) § 1039.627 What are the incentives for equipment manufacturers to use cleaner engines?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_627.md) - [40 C.F.R. § 1039.630 (2026) § 1039.630 What are the economic hardship provisions for equipment manufacturers?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_630.md) - [40 C.F.R. § 1039.635 (2026) § 1039.635 What are the hardship provisions for engine manufacturers?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_635.md) - [40 C.F.R. § 1039.645 (2026) § 1039.645 What special provisions apply to engines used for transportation refrigeration units?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_645.md) - [40 C.F.R. § 1039.655 (2026) § 1039.655 What special provisions apply to engines sold in American Samoa or the Commonwealth of the Northern Mariana Islands?](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_655.md) - [40 C.F.R. § 1039.665 (2026) § 1039.665 Special provisions for use of engines in emergency situations.](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_665.md) - [40 C.F.R. § 1039.670 (2026) § 1039.670 Approval of an emergency equipment field modification (EEFM).](https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_670.md) --- Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/CFR_T40_P1039_S1039_601. Check the current official text before relying on it. Not legal advice.