Section 1039.501 - How do I run a valid emission test?(a) Use the equipment and procedures for compression-ignition engines in 40 CFR part 1065 to determine whether engines meet the duty-cycle emission standards in subpart B of this part. Measure the emissions of all the exhaust constituents subject to emission standards as specified in 40 CFR part 1065. Measure CO2, N2O, and CH4 as described in § 1039.235 . Use the applicable duty cycles specified in §§ 1039.505 and 1039.510 .(b) Section 1039.515 describes the supplemental procedures for evaluating whether engines meet the not-to-exceed emission standards in subpart B of this part.(c) Measure smoke opacity using the procedures in 40 CFR part 1065, subpart L, for evaluating whether engines meet the smoke opacity standards in § 1039.105 , except that you may test two-cylinder engines with an exhaust muffler like those installed on in-use engines.(d) Use the fuels specified in § 1039.104(e) and 40 CFR part 1065 to perform valid tests. (1) 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) For diesel-fueled engines, use the appropriate diesel fuel specified in 40 CFR part 1065 for emission testing. Unless we specify otherwise, the appropriate diesel test fuel is the ultra low-sulfur diesel fuel. If we allow you to use a test fuel with higher sulfur levels, identify the test fuel in your application for certification and ensure that the emission control information label is consistent with your selection of the test fuel (see § 1039.135(c)(9) ). For example, do not test with ultra low-sulfur diesel fuel if you intend to label your engines to allow use of diesel fuel with sulfur concentrations up to 500 ppm.(e) The following provisions apply for engines using aftertreatment technology with infrequent regeneration events that may occur during testing: (1) Adjust measured emissions to account for aftertreatment technology with infrequent regeneration as described in § 1039.525 .(2) If your engine family includes engines with one or more emergency AECDs approved under § 1039.115(g)(4) or (5) , do not consider additional regenerations resulting from those AECDs when developing adjustments to measured values under this paragraph (e).(3) Invalidate a smoke test if active regeneration starts to occur during the test.(f) You may disable any AECDs that have been approved solely for emergency equipment applications under § 1039.115(g)(4) . Note that the emission standards do not apply when any of these AECDs are active.(g) You may use special or alternate procedures to the extent we allow them under 40 CFR 1065.10 .(h) 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.69 FR 39213, June 29, 2004, as amended at 70 FR 40463, July 13, 2005; 72 FR 53132, Sept. 18, 2007; 74 FR 56509, Oct. 30, 2009; 77 FR 34147, June 8, 2012; 79 FR 46373, Aug. 8, 2014; 81 FR 74137, Oct. 25, 2016; 88 FR 4659, Jan. 24, 2023 77 FR 34147, June 8,, 2012; 81 FR 74137, 12/27/2016; 88 FR 4659, 3/27/2023