eCFR Reference Browser

---

title: "40 CFR §90.309"

source: "https://www.ecfr.gov/current/title-40/section-90.309"

title_number: "40"

volume_number: "22"

chapter_number: "Unknown"

subchapter_code: "C"

subchapter_subject: "AIR PROGRAMS (CONTINUED)"

part_code: "90"

part_subject: "CONTROL OF EMISSIONS FROM NONROAD SPARK-IGNITION ENGINES AT OR BELOW 19 KILOWATTS"

subpart_code: "D"

subpart_subject: "Emission Test Equipment Provisions"

section_number: "90.309"

section_subject: "Engine intake air temperature measurement."

cfr_reference: "40 CFR 90.309"

title_name: "Title 40"

title_subject: "Protection of Environment"

parts_covered: "Parts 87 to 95"

revised_date: "Revised as of July 1, 2017"

publication_date: "As of July 1, 2017"

contains_description: "Containing a codification of documents of general applicability and future effect"

publication_info: "Published by the Office of the Federal Register National Archives and Records Administration as a Special Edition of the Federal Register"

---

(a)The measurement location must be within 10 cm of the engine intake system (i.e., the air cleaner, for most engines.)

(b)The temperature measurements must be accurate to within ±2 °C.

§90.309 - Engine intake air temperature measurement.