Section 1036.401 - Testing requirements for in-use engines(a) We may perform in-use testing of any engine family subject to the standards of this part, consistent with the Clean Air Act and the provisions of § 1036.235 .(b) This subpart describes a manufacturer-run field-testing program that applies for engines subject to compression-ignition standards under § 1036.104 . Note that the testing requirements of 40 CFR part 86, subpart T, continue to apply for engines subject to exhaust emission standards under 40 CFR part 86.(c) In-use test procedures for engines subject to spark-ignition standards apply as described in § 1036.530 . We won't require routine manufacturer-run field testing for Spark-ignition HDE, but the procedures of this subpart describe how to use field-testing procedures to measure emissions from engines installed in vehicles. Use good engineering judgment to apply the measurement procedures for fuels other than gasoline.(d) We may void your certificate of conformity for an engine family if you do not meet your obligations under this subpart. We may also void individual tests and require you to retest those vehicles or take other appropriate measures in instances where you have not performed the testing in accordance with the requirements described in this subpart. 81 FR 74004 , 12/27/2016; 88 FR 4487 , 3/27/2023