§ 86.1845-04 — Manufacturer in-use verification testing requirements.

40 CFR § 86.1845-04

• Title: Title 40: Protection of Environment
• Part: Part 86: Control of Emissions from New and In-Use Highway Vehicles and Engines
• Source: eCFR (current through Apr 9, 2026)

Text

§ 86.1845-04 Manufacturer in-use verification testing requirements. Link to an amendment published at 91 FR 7764, Feb. 18, 2026.

(a) General requirements. (1) Manufacturers of LDV, LDT, MDPV and complete HDV must test, or cause to have tested, a specified number of vehicles. Such testing must be conducted in accordance with the provisions of this section.

(2) Unless otherwise approved by the Administrator, no emission measurements made under the requirements of this section may be adjusted by Reactivity Adjustment Factors (RAFs).

(3) The following provisions apply regarding the possibility of residual effects from varying fuel sulfur levels:

(i) Vehicles certified under § 86.1811 must always measure emissions over the FTP, then over the HFET (if applicable), then over the US06. If a vehicle meets all the applicable emission standards except the FTP or HFET emission standard for NMOG+NOX, and a fuel sample from the tested vehicle (representing the as-received condition) has a measured fuel sulfur level exceeding 15 ppm when measured as described in 40 CFR 1065.710, the manufacturer may repeat the FTP and HFET measurements and use the new emission values as the official results for that vehicle. For all other cases, measured emission levels from the first test will be considered the official results for the test vehicle, regardless of any test results from additional test runs. Where repeat testing is allowed, the vehicle may operate for up to two US06 cycles (with or without measurement) before repeating the FTP and HFET measurements. The repeat measurements must include both FTP and HFET, even if the vehicle failed only one of those tests, unless the HFET is not required for a particular vehicle. Vehicles may not undergo any other vehicle preconditioning to eliminate fuel sulfur effects on the emission control system, unless we approve it in advance. This paragraph (a)(3)(i) does not apply for Tier 2 vehicles.

(ii) Upon a manufacturer's written request, prior to in-use testing, that presents information to EPA regarding pre-conditioning procedures designed solely to remove the effects of high sulfur in gasoline from vehicles produced through the 2007 model year, EPA will consider allowing such procedures on a case-by-case basis. EPA's decision will apply to manufacturer in-use testing conducted under this section and to any in-use testing conducted by EPA. Such procedures are not available for complete HDV. For model year 2007 and later Tier 2 vehicles, this provision can be used only in American Samoa, Guam, and the Commonwealth of the Northern Mariana Islands, and then only if low sulfur gasoline is determined by the Administrator to be unavailable in that specific location.

(4) Battery-related in-use testing requirements apply for battery electric vehicles and plug-in hybrid electric vehicles as described in paragraph (g) of this section.

(5) Certain medium-duty vehicles are also subject to in-use testing requirements to demonstrate compliance with off-cycle emission standards as described in paragraph (h) of this section.

(b) Low-mileage testing—(1) Test groups. Testing must be conducted for each test group and evaporative/refueling family as specified.

(2) Vehicle mileage. All test vehicles must have a minimum odometer mileage of 10,000 miles.

(3) Procuring test vehicles. For each test group, the minimum number of vehicles that must be tested is specified in table 1 (Table S04-06) and table 2 (Table S04-07) to this paragraph (b)(3). After testing the minimum number of vehicles of a specific test group as specified in Table S04-06 or S04-07, a manufacturer may test additional vehicles upon request and approval by the Agency prior to the initiation of the additional testing. Any additional testing must be completed within the testing completion requirements shown in § 86.1845-04(b)(4). The request and Agency approval (if any) shall apply to test groups on a case-by-case basis and apply only to testing under this paragraph (b). Separate approval will be required to test additional vehicles under paragraph (c) of this section. In addition to any testing that is required under Table S04-06 and Table S04-07, a manufacturer shall test one vehicle from each evaporative/refueling family for evaporative/refueling emissions. If a manufacturer believes it is unable to procure the required number of test vehicles meeting the specifications of this section, the manufacturer may request Administrator approval to either test a smaller number of vehicles or include vehicles that don't fully meet specifications. The request shall include a description of the methods the manufacturer has used to procure the required number of vehicles meeting specifications. The approval of any such request will be based on a review of the procurement efforts made by the manufacturer to determine if all reasonable steps have been taken to procure the required number of test vehicles meeting the specifications of this section.

Table 1 to Paragraph (b)(3)—Table S04-06—Small Volume Manufacturers

49 and 50 State total sales1	1-5000	5001-14,999
Low Mileage	Voluntary	0
High Mileage	Voluntary	2
1 Manufacturer's total annual sales.

Table 2 to Paragraph (b)(3)—Table S04-07—Large Volume Manufacturers

49 and 50 State annual sales 1	1-5000 2	5001-14,999 2	1-50,000 3	50,001-250,000	>250,000
Low Mileage	Voluntary	0	2	3	4
High Mileage	Voluntary	2	4	5	6
1 Sales by test group.
2 Total annual production of groups eligible for testing under small volume sampling plan is capped at a maximum of 14,999 vehicle 49 or 50 state annual sales, or a maximum of 4,500 vehicle California only sales per model year, per large volume manufacturer.
3 Sampling plan applies to all of a manufacturer's remaining groups in this sales volume category when the maximum annual cap on total sales of small groups eligible for the small volume sampling plan is exceeded.

(4) Completion of testing. Testing of the vehicles in a test group and evaporative/refueling family must be completed within 12 months of the end of production of that test group (or evaporative/refueling family) for that model year or a later date that we approve.

(5) Testing. (i) Each test vehicle of a test group shall be tested in accordance with the FTP and the US06 as described in subpart B of this part, when such test vehicle is tested for compliance with applicable exhaust emission standards under this subpart. Test vehicles subject to applicable exhaust CO2 emission standards under this subpart shall also be tested in accordance with the HFET as described in 40 CFR 1066.840.

(ii) For vehicles subject to Tier 3 p.m. standards, manufacturers must measure PM emissions over the FTP and US06 driving schedules for at least 50 percent of the vehicles tested under paragraph (b)(5)(i) of this section. For vehicles subject to Tier 4 p.m. standards, this test rate increases to 100 percent.

(iii) Starting with model year 2018 vehicles, manufacturers must demonstrate compliance with the Tier 3 leak standard specified in § 86.1813, if applicable, as described in this paragraph (b)(5)(iii). Manufacturers must evaluate each vehicle tested under paragraph (b)(5)(i) of this section, except that leak testing is not required for vehicles tested under paragraph (b)(5)(iv) of this section for diurnal emissions. In addition, manufacturers must evaluate at least one vehicle from each leak family for a given model year. Manufacturers may rely on OBD monitoring instead of testing as follows:

(A) A vehicle is considered to pass the leak test if the OBD system completed a leak check within the previous 750 miles of driving without showing a leak fault code.

(B) Whether or not a vehicle's OBD system has completed a leak check within the previous 750 miles of driving, the manufacturer may operate the vehicle as needed to force the OBD system to perform a leak check. If the OBD leak check does not show a leak fault, the vehicle is considered to pass the leak test.

(C) If the most recent OBD leak check from paragraph (b)(5)(iii)(A) or (B) of this section shows a leak-related fault code, the vehicle is presumed to have failed the leak test. Manufacturers may perform the leak measurement procedure described in 40 CFR 1066.985 for an official result to replace the finding from the OBD leak check.

(D) Manufacturers may not perform repeat OBD checks or leak measurements to over-ride a failure under paragraph (b)(5)(iii)(C) of this section.

(iv) For vehicles other than gaseous-fueled vehicles and electric vehicles, one test vehicle of each evaporative/refueling family shall be tested in accordance with the supplemental 2-diurnal-plus-hot-soak evaporative emission and refueling emission procedures described in subpart B of this part, when such test vehicle is tested for compliance with applicable evaporative emission and refueling standards under this subpart. For gaseous-fueled vehicles, one test vehicle of each evaporative/refueling family shall be tested in accordance with the 3-diurnal-plus-hot-soak evaporative emission and refueling emission procedures described in subpart B of this part, when such test vehicle is tested for compliance with applicable evaporative emission and refueling standards under this subpart. The test vehicles tested to fulfill the evaporative/refueling testing requirement of this paragraph (b)(5)(iv) will be counted when determining compliance with the minimum number of vehicles as specified in Table S04-06 and Table S04-07 (tables 1 and 2 to paragraph (b)(3) of this section) for testing under paragraph (b)(5)(i) of this section only if the vehicle is also tested for exhaust emissions under the requirements of paragraph (b)(5)(i) of this section.

(6) Test condition. Each test vehicle not rejected based on the criteria specified in appendix II to this subpart shall be tested in as-received condition.

(7) Diagnostic maintenance. A manufacturer may conduct subsequent diagnostic maintenance and/or testing of any vehicle. Any such maintenance and/or testing shall be reported to the Agency as specified in § 86.1847.

(c) High-mileage testing—(1) Test groups. Testing must be conducted for each test group and evaporative/refueling family as specified.

(2) Vehicle mileage. All test vehicles must have a minimum odometer mileage of 50,000 miles. At least one vehicle of each test group must have a minimum odometer mileage of 105,000 miles or 75 percent of the full useful life mileage, whichever is less. See § 86.1838-01(c)(2) for small-volume manufacturer mileage requirements.

(3) Procuring test vehicles. For each test group, the minimum number of vehicles that must be tested is specified in Table S04-06 and Table S04-07 (tables 1 and 2 to paragraph (b)(3) of this section). After testing the minimum number of vehicles of a specific test group as specified in Table S04-06 and Table S04-07, a manufacturer may test additional vehicles upon request and approval by the Agency prior to the initiation of the additional testing. Any additional testing must be completed within the testing completion requirements shown in § 86.1845-04(c)(4). The request and Agency approval (if any) shall apply to test groups on a case-by-case basis and apply only to testing under this paragraph (c). In addition to any testing that is required under Table S04-06 and Table S04-07, a manufacturer shall test one vehicle from each evaporative/refueling family for evaporative/refueling emissions. If a manufacturer believes it is unable to procure the required number of test vehicles meeting the specifications of this section, the manufacturer may request Administrator approval to either test a smaller number of vehicles or include vehicles that don't fully meet specifications. The request shall include a description of the methods the manufacturer has used to procure the required number of vehicles meeting specifications. The approval of any such request will be based on a review of the procurement efforts made by the manufacturer to determine if all reasonable steps have been taken to procure the required number of test vehicles meeting the specifications of this section.

(4) Initiation and completion of testing. Testing of a test group (or evaporative refueling family) must commence within 4 years of the end of production of the test group (or evaporative/refueling family) and be completed within 5 years of the end of production of the test group (or evaporative/refueling family) or a later date that we approve.

(5) Testing. (i) Each test vehicle shall be tested in accordance with the FTP and the US06 as described in subpart B of this part when such test vehicle is tested for compliance with applicable exhaust emission standards under this subpart. Test vehicles subject to applicable exhaust CO2 emission standards under this subpart shall also be tested in accordance with the HFET as described in 40 CFR 1066.840. One test vehicle from each test group shall be tested over the FTP at high altitude. The test vehicle tested at high altitude is not required to be one of the same test vehicles tested at low altitude. The test vehicle tested at high altitude is counted when determining the compliance with the requirements shown in Table S04-06 and Table S04-07 (tables 1 and 2 to paragraph (b)(3) of this section) or the expanded sample size as provided for in this paragraph (c).

(ii) For vehicles subject to Tier 3 p.m. standards, manufacturers must measure PM emissions over the FTP and US06 driving schedules for at least 50 percent of the vehicles tested under paragraph (c)(5)(i) of this section. For vehicles subject to Tier 4 p.m. standards, this test rate increases to 100 percent.

(iii) Starting with model year 2018 vehicles, manufacturers must evaluate each vehicle tested under paragraph (c)(5)(i) of this section to demonstrate compliance with the Tier 3 leak standard specified in § 86.1813, except that leak testing is not required for vehicles tested under paragraph (c)(5)(iv) of this section for diurnal emissions. In addition, manufacturers must evaluate at least one vehicle from each leak family for a given model year. Manufacturers may rely on OBD monitoring instead of testing as described in paragraph (b)(5)(iii) of this section.

(iv) For vehicles other than gaseous-fueled vehicles and electric vehicles, one test vehicle of each evaporative/refueling family shall be tested in accordance with the supplemental 2-diurnal-plus-hot-soak evaporative emission procedures described in subpart B of this part, when such test vehicle is tested for compliance with applicable evaporative emission and refueling standards under this subpart. For gaseous-fueled vehicles, one test vehicle of each evaporative/refueling family shall be tested in accordance with the 3-diurnal-plus-hot-soak evaporative emission procedures described in subpart B of this part, when such test vehicle is tested for compliance with applicable evaporative emission and refueling standards under this subpart. The vehicles tested to fulfill the evaporative/refueling testing requirement of this paragraph (c)(5)(iv) will be counted when determining compliance with the minimum number of vehicles as specified in Tables S04-06 and S04-07 (tables 1 and 2 to paragraph (b)(3) of this section) for testing under paragraph (c)(5)(i) of this section only if the vehicle is also tested for exhaust emissions under the requirements of paragraph (c)(5)(i) of this section .

(6) Test condition. Each test vehicle not rejected based on the criteria specified in appendix II to this subpart shall be tested in as-received condition.

(7) Diagnostic maintenance. A manufacturer may conduct subsequent diagnostic maintenance and/or testing on any vehicle. Any such maintenance and/or testing shall be reported to the Agency as specified in § 86.1847-01.

(d) Test vehicle procurement. Vehicles tested under this section shall be procured as follows:

(1) Vehicle ownership. Vehicles shall be procured from the group of persons who own or lease vehicles registered in the procurement area. Vehicles shall be procured from persons which own or lease the vehicle, excluding commercial owners/lessees owned or controlled by the vehicle manufacturer, using the procedures described in appendix I to this subpart. See § 86.1838-01(c)(2)(i) for small volume manufacturer requirements.

(2) Geographical limitations. (i) Test groups certified to 50-state standards: For low altitude testing no more than fifty percent of the test vehicles may be procured from California. The test vehicles procured from the 49-state area must be procured from a location with a heating degree day 30-year annual average equal to or greater than 4,000.

(ii) Test groups certified to 49-state standards: The test vehicles procured from the 49-state area must be procured from a location with a heating degree day 30-year annual average equal to or greater than 4,000.

(iii) Vehicles procured for high altitude testing may be procured from any area located above 4,000 feet.

(3) Rejecting candidate vehicles. Vehicles may be rejected for procurement or testing under this section if they meet one or more of the rejection criteria in appendix II to this subpart. Vehicles may also be rejected after testing under this section if they meet one or more of the rejection criteria in appendix II to this subpart. Any vehicle rejected after testing must be replaced in order that the number of test vehicles in the sample comply with the sample size requirements of this section. Any post-test vehicle rejection and replacement procurement and testing must take place within the testing completion requirements of this section.

(e) Testing facilities, procedures, quality assurance and quality control — (1) Lab equipment and procedural requirements. The manufacturer shall utilize a test laboratory that is in accordance with the equipment and procedural requirements of subpart B of this part to conduct the testing required by this section.

(2) Notification of test facility. The manufacturer shall notify the Agency of the name and location of the testing laboratory(s) to be used to conduct testing of vehicles of each model year conducted pursuant to this section. Such notification shall occur at least thirty working days prior to the initiation of testing of the vehicles of that model year.

(3) Correlation. The manufacturer shall document correlation traceable to the Environmental Protection Agency's National Vehicle and Fuel Emission Laboratory for its test laboratory utilized to conduct the testing required by this section.

(f) NMOG and formaldehyde. The following provisions apply for measuring NMOG and formaldehyde:

(1) A manufacturer must conduct in-use testing on a test group by determining NMOG exhaust emissions using the same methodology used for certification, as described in 40 CFR 1066.635.

(2) For flexible-fueled vehicles certified to NMOG (or NMOG+NOX) standards, the manufacturer may ask for EPA approval to demonstrate compliance using an equivalent NMOG emission result calculated from a ratio of ethanol NMOG exhaust emissions to gasoline NMHC exhaust emissions. Ethanol NMOG exhaust emissions are measured values from testing with the ethanol test fuel, expressed as NMOG. Gasoline NMHC exhaust emissions are measured values from testing with the gasoline test fuel, expressed as NMHC. This ratio must be established during certification for each emission-data vehicle for the applicable test group. Use good engineering judgment to establish a different ratio for each duty cycle or test interval as appropriate. Identify the ratio values you develop under this paragraph (f)(2) and describe the duty cycle or test interval to which they apply in the Part II application for certification. Calculate the equivalent NMOG emission result by multiplying the measured gasoline NMHC exhaust emissions for a given duty cycle or test interval by the appropriate ratio.

(3) If the manufacturer measures NMOG as described in 40 CFR 1066.635(a), it must also measure and report HCHO emissions. As an alternative to measuring the HCHO content, if the manufacturer measures NMOG as permitted in 40 CFR 1066.635(c), the Administrator may approve, upon submission of supporting data by a manufacturer, the use of HCHO to NMHC ratios. To request the use of HCHO to NMHC ratios, the manufacturer must establish during certification testing the ratio of measured HCHO exhaust emissions to measured NMHC exhaust emissions for each emission-data vehicle for the applicable test group. The results must be submitted to the Administrator with the Part II application for certification. Following approval of the application for certification, the manufacturer may conduct in-use testing on the test group by measuring NMHC exhaust emissions rather than HCHO exhaust emissions. The measured NMHC exhaust emissions must be multiplied by the HCHO to NMHC ratio submitted in the application for certification for the test group to determine the equivalent HCHO exhaust emission values for the test vehicle. The equivalent HCHO exhaust emission values must be compared to the HCHO exhaust emission standard applicable to the test group.

(g) Battery testing. Manufacturers of battery electric vehicles and plug-in hybrid electric vehicles must perform in-use testing related to battery monitor accuracy and battery durability for those vehicles as described in § 86.1815-27. Except as otherwise provided in § 86.1815-27(h), perform Part A testing for each monitor family as follows to verify that SOCE monitors meet accuracy requirements:

(1) Determine accuracy by measuring SOCE from in-use vehicles using the procedures specified in § 86.1815-27(c) and comparing the measured values to the SOCE value displayed on the monitor at the start of testing.

(2) Perform low-mileage testing of the vehicles in a monitor family within 24 months of the end of production of that monitor family for that model year. All test vehicles must have a minimum odometer mileage of 20,000 miles.

(3) Perform high-mileage testing of the vehicles in a monitor family by starting the test program within 4 years of the end of production of the monitor family and completing the test program within 5 years of the end of production of the monitor family. All test vehicles must have a minimum odometer mileage of 40,000 miles.

(4) Select test vehicles as described in paragraphs (b)(6), (c)(6), and (d)(1) and (3) of this section from the United States. Send notification regarding test location as described in paragraph (e)(2) of this section.

(5) You may perform diagnostic maintenance as specified in paragraph (b)(7) and (c)(7) of this section.

(6) See § 86.1838-01(b)(2) for a testing exemption that applies for small-volume monitor families.

(h) Off-cycle testing for high-GCWR medium-duty vehicles. Medium-duty vehicles that are subject to off-cycle standards under § 86.1811-27(e) are subject to in-use testing requirements described in 40 CFR part 1036, subpart E, and 40 CFR 1036.530, with the following exceptions and clarifications:

(1) In-use testing requirements apply for both vehicles with spark-ignition engines and vehicles with compression-ignition engines.

(2) References to “engine family” should be understood to mean “test group”.

(3) In our test order we may include the following requirements and specifications:

(i) We may select any vehicle configuration for testing. We may also specify that the selected vehicle have certain optional features.

(ii) We may allow the vehicle manufacturer to arrange for the driver of a test vehicle to be an employee or a hired contractor, rather than the vehicle owner.

(iii) We may specify certain routes or types of driving.

(4) Within 45 days after we direct you to perform testing under this paragraph (h), send us a proposed test plan that meets the provisions in this paragraph (h)(4) in addition to what we specify in 40 CFR 1036.410. EPA must approve the test plan before the manufacturer may start testing. EPA approval will be based on a determination that the test plan meets all applicable requirements. The test plan must include the following information:

(i) Describe how you will select vehicles, including consideration of available options and features, to properly represent in-use performance for the selected vehicle configuration.

(ii) Describe any planned inspection or maintenance before testing the vehicle, along with any criteria for rejecting a candidate vehicle.

(iii) Describe test routes planned for testing. The test route must target a specific total duration or distance, including at least three hours of driving with non-idle engine operation. The test route must represent normal driving, including a broad range of vehicle speeds and accelerations and a reasonable amount of operation at varying grades. If the completed test route does not include enough windows for any bin as specified in paragraph (h)(8) of this section, repeat the drive over the approved test route.

(iv) Describe your plan for vehicle operation to include at least 50 percent of non-idle operation with gross combined weight at least 70 percent of GCWR. Trailers used for testing must meet certain specifications as follows:

(A) Trailers must comply with requirements in Row D through Row L of Table 1 of SAE J2807 (incorporated by reference, see § 86.1); however, the frontal area of the trailer may not exceed the vehicle manufacturer's specified maximum frontal area for towing. Trailers over 24,000 pounds must have a frontal area between 60 and 75 ft ².

(B) You may ask us to approve the use of a trailer not meeting SAE J2807 specifications. This may apply, for example, if the trailer has tires that are different than but equivalent to the specified tires. In your request, describe the alternative trailer's specifications, why you are using it, and how it is more representative of in-use operation than a trailer meeting the specifications in paragraph (h)(4)(iv)(A) of this section. Rather than demonstrating representativeness, you may instead describe why it is infeasible to use a trailer meeting the specifications in paragraph (h)(4)(iv)(A) of this section. We will consider whether your request is consistent with good engineering judgment.

(5) The accuracy margins in 40 CFR 1036.420(a) do not apply for vehicles with spark-ignition engines, or for vehicles with compression-ignition engines for demonstrating compliance with standards based on measurement procedures with 3-bin moving average windows.

(6) Determine a reference CO2 emission rate, eCO2FTPFCL, as described in 40 CFR 1036.635(a)(1) or based on measured values from any chassis FTP driving cycles under 40 CFR part 1066, subpart I, that is used for reporting data from an emission data vehicle or a fuel economy data vehicle, as follows:

Equation 1 to Paragraph (h)(6) Where: mCO2FTP = CO2 emission mass in grams emitted over the FTP driving cycle. dFTP = measured driving distance in miles. WFTP = work performed over the FTP. i = an indexing variable that represents a 1 Hz OBD time counter over the course of the FTP drive. N = total number of measurements over the FTP duty cycle = 1874. fn = engine speed for each point, i, starting from the start of the FTP drive at i = 1, collected from OBD PID $0C. T = engine torque in N·m for each point, i, starting from i = 1. Calculate T by subtracting Friction Torque (PID $8E) from Indicated Torque (PID $62) (both PIDs are percentages) and then multiplying by the reference torque (PID $63). Set torque to zero if friction torque is greater than indicated torque. Δt = 1/frecord frecord = the data recording frequency. Example: mCO2FTP = 10,961 g N = 1874 f1 = 687.3 r/min = 71.97 rad/s f2 = 689.7 r/min = 72.23 rad/s T1 = 37.1 ft·lbf = 50.3 N·m T2 = 37.2 ft·lbf = 50.4 N·m frecord = 1 Hz Δt = 1/1 = 1 s = 0.000277 hr WFTP = 71.97 · 50.3 · 1.0 + 72.23 · 50.4 · 1.0 + · · · ƒn1874 · T1874 · Δt1874 WFTP = 53,958,852 W·s = 20.1 hp·hr eCO2FTPFCL = 545.3 g/hp·hr

(7) For testing based on the 3-bin moving average windows, identify the appropriate bin for each of the 300 second test intervals based on its normalized CO2 emission mass, mCO2,norm,testinterval, instead of the bin definitions in 40 CFR 1036.530(f), as follows:

Table 3 to paragraph (h)(7) of § 86.1845-04—Criteria for Off-Cycle Bins for 3-Bin Moving Average Windows

Bin	Normalized CO2 emission mass over the 300 second test interval
Bin 1	mCO2,norm,testinterval ≤ 6.00%
Bin 2a	6.00% < mCO2,norm,testinterval ≤ 20.00%
Bin 2b	mCO2,norm,testinterval > 20.00%

(8) For testing based on 3-bin moving average windows, calculate the off-cycle emissions quantity for Bin 2a and Bin 2b using the method described in 40 CFR 1036.530 for Bin 2. Each bin is valid for evaluating test results only if it has at least 2,400 windows.

[89 FR 28183, Apr. 18, 2024]