---
kind: "section"
citation: "40 C.F.R. § 1045.5"
title: "40"
number: "1045.5"
heading: "Which engines are excluded from this part's requirements?"
url: "https://uscodex.org/cfr/40/1045.5"
---

# §1045.5. Which engines are excluded from this part's requirements?

- (a) **Auxiliary engines.** The exhaust emission standards of this part do not apply to auxiliary marine engines. See 40 CFR part [90](/cfr/40/part90.md), [1048](/cfr/40/part1048.md), or 1054 for the exhaust emission standards that apply. Evaporative emission standards apply as specified in [§ 1045.112](/cfr/40/1045.112.md).
- (b) **Hobby engines and vessels.** This part does not apply with respect to reduced-scale models of vessels that are not capable of transporting a person.
- (c) **Large natural gas engines.** Propulsion marine engines powered by natural gas with maximum engine power at or above 250 kW are deemed to be compression-ignition engines. These engines are therefore subject to all the requirements of [40 CFR part 1042](/cfr/40/part1042.md) instead of this part even if they would otherwise meet the definition of “spark-ignition” in [§ 1045.801](/cfr/40/1045.801.md).

## Notes

### Authority

Authority: 42 U.S.C. 7401-7671q.

### Source

Source: 73 FR 59194, Oct. 8, 2008, unless otherwise noted.