Section 1042.501 - 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 §§ 1042.101 or 1042.104 . Measure the emissions of all regulated pollutants as specified in 40 CFR part 1065. Use the applicable duty cycles specified in § 1042.505 . The following exceptions from the 40 CFR part 1065 procedures apply: (1) If you perform discrete-mode testing and use only one batch fuel measurement to determine your mean raw exhaust flow rate, you must target a constant sample flow rate over the mode. Verify proportional sampling as described in 40 CFR 1065.545 using the mean raw exhaust molar flow rate paired with each recorded sample flow rate.(2) If you perform discrete-mode testing, you may verify proportional sampling over the whole duty cycle instead of verifying proportional sampling for each discrete mode.(b) Section 1042.515 describes the supplemental test procedures for evaluating whether engines meet the not-to-exceed emission standards in § 1042.101(c) .(c) Use the fuels and lubricants specified in 40 CFR part 1065, subpart H, for all the testing we require in this part, except as specified in this section and § 1042.515 . (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, subpart H, for emission testing. Unless we specify otherwise, the appropriate diesel test fuel for Category 1 and Category 2 engines 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. Unless we specify otherwise, the appropriate diesel test fuel for Category 3 engines is the high-sulfur diesel fuel. For Category 2 and Category 3 engines, you may ask to use commercially available diesel fuel similar but not necessarily identical to the applicable fuel specified in 40 CFR part 1065, subpart H; we will approve your request if you show us that it does not affect your ability to demonstrate compliance with the applicable emission standards.(3) For Category 1 and Category 2 engines that are expected to use a type of fuel (or mixed fuel) other than diesel fuel (such as natural gas, methanol, or residual fuel), use a commercially available fuel of that type for emission testing. If a given engine is designed to operate on different fuels, we may (at our discretion) require testing on each fuel. Propose test fuel specifications that take into account the engine design and the properties of commercially available fuels. Describe these test fuel specifications in the application for certification.(d) Adjust measured emissions to account for aftertreatment technology with infrequent regeneration as described in § 1042.525 .(e) Duty-cycle testing is limited to atmospheric pressures between 91.000 and 103.325 kPa.(f) You may use special or alternate procedures to the extent we allow them under 40 CFR 1065.10 .(g) For Category 3 engines, instead of test data collected as specified in 40 CFR part 1065, you may submit test data for NOX, HC, and CO emissions that were collected as specified in the NOX Technical Code (incorporated by reference in § 1042.910 ). For example, this allowance includes the allowance to perform the testing using test fuels allowed under the NOX Technical Code that do not meet the sulfur specifications of this section. We may require you to include a brief engineering analysis showing how these data demonstrate that your engines would meet the applicable emission standards if you had used the test procedures specified in 40 CFR part 1065.(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. 73 FR 37243 , June 30, 2008, as amended at 74 FR 56509 , Oct. 30, 2009; 75 FR 23005 , Apr. 30, 2010; 81 FR 74149 , Oct. 25, 2016