StacksVerified U.S. regulatory reference

40 CFR Part 1039, Appendix I

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov

The following standards, which EPA originally adopted under 40 CFR part 89, apply to nonroad compression-ignition engines produced before the model years specified in § 1039.1:

(a) Tier 1 standards apply as summarized in the following table:

Rated power (kW)Starting model yearNOXHCNOX + NMHCCOPM
kW< 82000|10.581
8 ≤ kW < 192000|9.56.60.8
19 ≤ kW < 371999|9.55.50.8
37 ≤ kW < 7519989.2
75 ≤ kW < 13019979.2
130 ≤ kW ≤ 56019969.21.3| 11.40.54
kW > 56020009.21.3| 11.40.54

(b) Tier 2 standards apply as summarized in the following table:

Rated power (kW)Starting model yearNOX + NMHCCOPM
kW< 820057.580.8
8 ≤ kW < 1920057.56.60.8
19 ≤ kW < 3720047.55.50.6
37 ≤ kW < 7520047.550.4
75 ≤ kW < 13020036.650.3
130 ≤ kW < 22520036.63.50.2
225 ≤ kW < 45020016.43.50.2
450 ≤ kW ≤ 56020026.43.50.2
kW > 56020066.43.50.2

(c) Tier 3 standards apply as summarized in the following table:

Rated power(kW)Startingmodel yearNOX+NMHCCOPM
37 ≤ kW < 7520084.750.4
75 ≤ kW < 1302007450.3
130 ≤ kW ≤ 560200643.50.2

(d) Tier 1 through Tier 3 standards applied only for discrete-mode steady-state testing. There were no not-to-exceed standards or transient testing.

[86 FR 34507, June 29, 2021, as amended at 88 FR 4660, Jan. 24, 2023]