---
kind: "section"
citation: "40 C.F.R. § 1045.501"
title: "40"
number: "1045.501"
heading: "How do I run a valid emission test?"
url: "https://uscodex.org/cfr/40/1045.501"
---

# §1045.501. How do I run a valid emission test?

- (a) **Applicability.** This subpart is addressed to you as a manufacturer but it applies equally to anyone who does testing for you, and to us when we perform testing to determine if your engines meet emission standards.
- (b) **General requirements.** Use the equipment and procedures for spark-ignition engines in [40 CFR part 1065](/cfr/40/part1065.md) to determine whether engines meet the duty-cycle emission standards in §§ [1045.103](/cfr/40/1045.103.md) and [1045.105](/cfr/40/1045.105.md). Measure the emissions of all exhaust constituents subject to emissions standards as specified in [40 CFR part 1065](/cfr/40/part1065.md). Measure CO2, N2O, and CH4 as described in [§ 1045.235](/cfr/40/1045.235.md). Use the applicable duty cycles specified in [§ 1045.505](/cfr/40/1045.505.md). [Section 1045.515](/cfr/40/1045.515.md) describes the supplemental procedures for evaluating whether engines meet the not-to-exceed emission standards in [§ 1045.107](/cfr/40/1045.107.md).
- (c) **Fuels.** Use the fuels and lubricants specified in [40 CFR part 1065](/cfr/40/part1065.md), [subpart H](/cfr/40/subpartH.md), for all the testing we require in this part, except as specified in [§ 1045.515](/cfr/40/1045.515.md).
  - (1) Use gasoline meeting the specifications described in [40 CFR 1065.710(c)](/cfr/40/1065.710.md?p=c) for general testing. For service accumulation, use the test fuel or any commercially available fuel that is representative of the fuel that in-use engines will use.
  - (2) You may alternatively use ethanol-blended fuel meeting the specifications described in [40 CFR 1065.710(b)](/cfr/40/1065.710.md?p=b) for general testing without our advance approval. If you use the ethanol-blended fuel for certifying a given engine family, you may also use it for production-line testing or any other testing you perform for that engine family under this part. If you use the ethanol-blended fuel for certifying a given engine family, we may use the ethanol-blended fuel or the specified neat gasoline test fuel with that engine family.
- (d) **Laboratory conditions.** Ambient conditions for duty-cycle testing must be within ranges specified in [40 CFR 1065.520](/cfr/40/1065.520.md), subject to the provisions of [§ 1045.115(d)](/cfr/40/1045.115.md?p=d). Emissions may not be corrected for the effects of test temperature or pressure. Humidity levels must represent actual in-use humidity levels; however, you may correct emissions for humidity as specified in [40 CFR 1065.670](/cfr/40/1065.670.md).
- (e) **Engine stabilization.** Instead of the provisions of [40 CFR 1065.405](/cfr/40/1065.405.md), you may consider emission levels stable without measurement after 12 hours of engine operation.
- (f) **Maximum test speed.** Instead of the provisions of [40 CFR 1065.510(f)](/cfr/40/1065.510.md?p=f), you may declare a value of maximum test speed for laboratory testing that is within 500 rpm of the corresponding measured value for maximum test speed.
- (g) **Special and alternate procedures.** If you are unable to run the duty cycle specified in this part for your engine (such as with constant-speed engines), use an alternate test cycle that will result in a cycle-weighted emission measurement equivalent to the expected average in-use emissions. This cycle must be approved under [40 CFR 1065.10](/cfr/40/1065.10.md). You may use other special or alternate procedures to the extent we allow them under [40 CFR 1065.10](/cfr/40/1065.10.md).
- (h) **Laboratory testing with portable analyzers.** You may use field-grade equipment for any laboratory testing with high-performance engines, as specified in [40 CFR 1065.901(b)](/cfr/40/1065.901.md?p=b), without requesting approval.

## Notes

### Amendments

[73 FR 59194, Oct. 8, 2008, as amended at 74 FR 56510, Oct. 30, 2009; 86 FR 34514, June 29, 2021]

### Authority

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

### Source

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

### Amendments

[73 FR 59194, Oct. 8, 2008, as amended at 74 FR 56510, Oct. 30, 2009; 86 FR 34514, June 29, 2021]