---
kind: "range"
citation: "40 C.F.R. §§ 1036.240–1036.246"
title: "40"
from: "1036.240"
to: "1036.246"
count: 3
url: "https://uscodex.org/cfr/40/1036.240..1036.246"
---

# §1036.240. Demonstrating compliance with criteria pollutant emission standards.

- (a) For purposes of certification, your engine family is considered in compliance with the duty-cycle emission standards in § [1036.104(a)(1)](/cfr/40/1036.104.md?p=a-1) and [(2)](/cfr/40/1036.104.md?p=a-2) if all emission-data engines representing that family have test results showing official emission results and deteriorated emission levels at or below these standards (including all corrections and adjustments). This also applies for all test points for emission-data engines within the family used to establish deterioration factors. Note that your FELs are considered to be the applicable emission standards with which you must comply if you participate in the ABT program in [subpart H](/cfr/40/subpartH.md) of this part. Use good engineering judgment to demonstrate compliance with off-cycle standards throughout the useful life.
- (b) Your engine family is deemed not to comply if any emission-data engine representing that family has test results showing an official emission result or a deteriorated emission level for any pollutant that is above an applicable emission standard (including all corrections and adjustments). Similarly, your engine family is deemed not to comply if any emission-data engine representing that family has test results showing any emission level above the applicable off-cycle emission standard for any pollutant. This also applies for all test points for emission-data engines within the family used to establish deterioration factors.
- (c) To compare emission levels from the emission-data engine with the applicable duty-cycle emission standards, apply deterioration factors to the measured emission levels for each pollutant. [Section 1036.245](/cfr/40/1036.245.md) specifies how to test engines and engine components to develop deterioration factors that represent the deterioration expected in emissions over your engines' useful life. [Section 1036.246](/cfr/40/1036.246.md) describes how to confirm or modify deterioration factors based on in-use verification testing. Your deterioration factors must take into account any available data from other in-use testing with similar engines. Small manufacturers may use assigned deterioration factors that we establish. Apply deterioration factors as follows:
  - (1) **Additive deterioration factor for exhaust emissions.** Except as specified in [paragraph (c)(2)](#c-2) of this section, use an additive deterioration factor for exhaust emissions. An additive deterioration factor is the difference between exhaust emissions at the end of the useful life and exhaust emissions at the low-hour test point. In these cases, adjust the official emission results for each tested engine at the selected test point by adding the factor to the measured emissions. If the factor is less than zero, use zero. Additive deterioration factors must be specified to one more decimal place than the applicable standard.
  - (2) **Multiplicative deterioration factor for exhaust emissions.** Use a multiplicative deterioration factor if good engineering judgment calls for the deterioration factor for a pollutant to be the ratio of exhaust emissions at the end of the useful life to exhaust emissions at the low-hour test point. For example, if you use aftertreatment technology that controls emissions of a pollutant proportionally to engine-out emissions, it is often appropriate to use a multiplicative deterioration factor. Adjust the official emission results for each tested engine at the selected test point by multiplying the measured emissions by the deterioration factor. If the factor is less than one, use one. A multiplicative deterioration factor may not be appropriate in cases where testing variability is significantly greater than engine-to-engine variability. Multiplicative deterioration factors must be specified to one more significant figure than the applicable standard.
  - (3) **Sawtooth and other nonlinear deterioration patterns.** The deterioration factors described in paragraphs [(c)(1)](#c-1) and [(2)](#c-2) of this section assume that the highest useful life emissions occur either at the end of useful life or at the low-hour test point. The provisions of this [paragraph (c)(3)](#c-3) apply where good engineering judgment indicates that the highest useful life emissions will occur between these two points. For example, emissions may increase with service accumulation until a certain maintenance step is performed, then return to the low-hour emission levels and begin increasing again. Such a pattern may occur with battery-based hybrid powertrains. Base deterioration factors for engines with such emission patterns on the difference between (or ratio of) the point at which the highest emissions occur and the low-hour test point. Note that this [paragraph (c)(3)](#c-3) applies for maintenance-related deterioration only where we allow such critical emission-related maintenance.
  - (4) **Dual-fuel and flexible-fuel engines.** In the case of dual-fuel and flexible-fuel engines, apply deterioration factors separately for each fuel type. You may accumulate service hours on a single emission-data engine using the type of fuel or the fuel mixture expected to have the highest combustion and exhaust temperatures; you may ask us to approve a different fuel mixture if you demonstrate that a different criterion is more appropriate.
  - (5) **Deterioration factor for crankcase emissions.** If engines route crankcase emissions into the ambient atmosphere or into the exhaust downstream of exhaust aftertreatment, you must account for any increase in crankcase emissions throughout the useful life using good engineering judgment. Use separate deterioration factors for crankcase emissions of each pollutant (either multiplicative or additive).
- (d) Determine the official emission result for each pollutant to at least one more decimal place than the applicable standard. Apply the deterioration factor to the official emission result, as described in [paragraph (c)](#c) of this section, then round the adjusted figure to the same number of decimal places as the emission standard. Compare the rounded emission levels to the emission standard for each emission-data engine.
- (e) **You do not need deterioration factors to demonstrate compliance with off-cycle standards.** However, for engines designed to discharge crankcase emissions to the ambient atmosphere, you must determine deteriorated emission levels to represent crankcase emissions at the end of useful life for purposes of demonstrating compliance with off-cycle emission standards. Determine an official brake-specific crankcase emission result for each pollutant based on operation over the FTP duty cycle. Also determine an official crankcase emission result for NOX in g/hr from the idle portion of any of the duty cycles specified in [subpart F](/cfr/40/subpartF.md) of this part. Apply crankcase deterioration factors to all these official crankcase emission results as described in [paragraph (c)](#c) of this section, then round the adjusted figures to the same number of decimal places as the off-cycle emission standards in [§ 1036.104(a)(3)](/cfr/40/1036.104.md?p=a-3).

# §1036.245. Deterioration factors for exhaust emission standards.


This section describes how to determine deterioration factors, either with pre-existing test data or with new emission measurements. Apply these deterioration factors to determine whether your engines will meet the duty-cycle emission standards throughout the useful life as described in [§ 1036.240](/cfr/40/1036.240.md). The provisions of this section and the verification provisions of [§ 1036.246](/cfr/40/1036.246.md) apply for all engine families starting in model year 2027; you may optionally use these provisions to determine and verify deterioration factors for earlier model years.

- (a) You may ask us to approve deterioration factors for an engine family based on an engineering analysis of emission measurements from similar highway or nonroad engines if you have already given us these data for certifying the other engines in the same or earlier model years. Use good engineering judgment to decide whether the two engines are similar. We will approve your request if you show us that the emission measurements from other engines reasonably represent in-use deterioration for the engine family for which you have not yet determined deterioration factors.
- (b) [Reserved]
- (c) If you are unable to determine deterioration factors for an engine family under [paragraph (a)](#a) of this section, select engines, subsystems, or components for testing. Determine deterioration factors based on service accumulation and related testing to represent the deterioration expected from in-use engines over the useful life, including crankcase emissions. You may perform maintenance on emission-data engines as described in [§ 1036.125](/cfr/40/1036.125.md) and [40 CFR part 1065](/cfr/40/part1065.md), subpart E. Use good engineering judgment for all aspects of the effort to establish deterioration factors under this [paragraph (c)](#c). Send us your test plan for our preliminary approval under [§ 1036.210](/cfr/40/1036.210.md). You may apply deterioration factors based on testing under this [paragraph (c)](#c) to multiple engine families, consistent with the provisions in [paragraph (a)](#a) of this section. Determine deterioration factors based on a combination of minimum required engine dynamometer aging hours and accelerated bench-aged aftertreatment as follows:
  - (1) Select an emission-data engine and aftertreatment devices and systems that can be assembled into a certified configuration to represent the engine family. Stabilize the engine and aftertreatment devices and systems, together or separately, to prepare for emission measurements. Perform low-hour emission measurement once the engine has operated with aftertreatment long enough to stabilize the emission control. Measure emissions of all regulated pollutants while the engine operates over all applicable duty cycles on an engine dynamometer as described in subpart F of this part.
  - (2) Perform additional service accumulation as described in [paragraph (c)(3)](#c-3) of this section on an engine dynamometer meeting at least the following minimum specifications:
  - (3) Perform service accumulation in the laboratory by operating the engine or hybrid powertrain repeatedly over one of the following test sequences, or a different test sequence that we approve in advance:
    - (i) **Use duty-cycle sequence 1 for operating any engine on an engine dynamometer, as follows—**
      - (A) **Operate at idle for 2 hours.**
      - (B) **Operate for 105 ± 1 hours over a repeat sequence of one FTP followed by one RMC.**
      - (C) **Operate over one LLC.**
      - (D) **Operate at idle for 2 hours.**
      - (E) **Shut down the engine for cooldown to ambient temperature.**
    - (ii) Duty-cycle sequence 2 is based on operating over the LLC and the vehicle-based duty cycles from [40 CFR part 1037](/cfr/40/part1037.md). Select the vehicle subcategory and vehicle configuration from [§ 1036.540](/cfr/40/1036.540.md) or [§ 1036.545](/cfr/40/1036.545.md) with the highest reference cycle work for each vehicle-based duty cycle. Operate the engine as follows for duty-cycle sequence 2:
      - (A) **Operate at idle for 2 hours.**
      - (B) Operate for 105 ± 1 hours over a repeat sequence of one Heavy-duty Transient Test Cycle, then one 55 mi/hr highway cruise cycle, and then one 65 mi/hr highway cruise cycle.
      - (C) **Operate over one LLC.**
      - (D) **Operate at idle for 2 hours.**
      - (E) **Shut down the engine for cooldown to ambient temperature.**
  - (4) Perform all the emission measurements described in [paragraph (c)(1)](#c-1) of this section when the engine has reached the minimum service accumulation specified in [paragraph (c)(2)](#c-2) of this section, and again after you finish service accumulation in the laboratory if your service accumulation exceeds the values specified in [paragraph (c)(2)](#c-2) of this section.
  - (5) Determine the deterioration factor based on a combination of actual and simulated service accumulation represented by a number of hours of engine operation calculated using the following equation:
  - (6) Perform accelerated bench aging of aftertreatment devices to represent normal engine operation over the useful life using the service accumulation hours determined in [paragraph (c)(5)](#c-5) of this section. Design your bench aging to represent 10,000 hours of in-use engine operation for every 1,000 hours of accelerated bench aging. Use the accelerated bench-aging procedure in [40 CFR 1065.1131 through 1065.1145](/cfr/40/1065.1131..1065.1145.md) or get our advance approval to use a different procedure that adequately that accounts for thermal and chemical degradation. For example, this might involve testing consistent with the analogous procedures that apply for light-duty vehicles under [40 CFR part 86](/cfr/40/part86.md), subpart S.
  - (7) After bench-aging aftertreatment devices, install or reinstall those aftertreatment devices and systems on an emission-data engine (or an equivalent engine) that has been stabilized without aftertreatment. Ensure that the aftertreatment is installed such that the engine is in a certified configuration to represent the engine family.
  - (8) Operate the engine with the bench-aged aftertreatment devices to stabilize emission controls for at least 100 hours on an engine dynamometer.
  - (9) **Once stabilization is complete, repeat the low-hour emission measurements.**
  - (10) Calculate deterioration factors by comparing exhaust emissions with the bench-aged aftertreatment and exhaust emissions at the low-hour test point. Create a linear curve fit if testing includes intermediate test points. Calculate deterioration factors based on measured values, without extrapolation.
- (d) If you determine deterioration factors as described in [paragraph (c)](#c) of this section, you may apply those deterioration factors in later years for engine families that qualify for carryover certification as described in [§ 1036.235(d)](/cfr/40/1036.235.md?p=d). You may also apply those deterioration factors for additional engine families as described in [paragraph (a)](#a) of this section.
- (e) **Include the following information in your application for certification—**
  - (1) If you use test data from a different engine family, explain why this is appropriate and include all the emission measurements on which you base the deterioration factors. If the deterioration factors for the new engine family are not identical to the deterioration factors for the different engine family, describe your engineering analysis to justify the revised values and state that all your data, analyses, evaluations, and other information are available for our review upon request.
  - (2) If you determined deterioration factors under [paragraph (c)](#c) of this section, include the following information in the first year that you use those deterioration factors:
    - (i) Describe your accelerated bench aging or other procedures to represent full-life service accumulation for the engine's emission controls.
    - (ii) Describe how you prepared the test engine before and after installing aftertreatment systems to determine deterioration factors.
    - (iii) **Identify the power rating of the emission-data engine used to determine deterioration factors.**

# §1036.246. Verifying deterioration factors.


We may require you to test in-use engines as described in this section to verify that the deterioration factors you determined under [§ 1036.245](/cfr/40/1036.245.md) are appropriate.

- (a) Select and prepare in-use engines representing the engine family we identify for verification testing under this section as follows:
  - (1) You may recruit candidate engines any time before testing. This may involve creating a pool of candidate engines and vehicles in coordination with vehicle manufacturers and vehicle purchasers to ensure availability and to confirm a history of proper maintenance. You may meet the testing requirements of this section by repeating tests on a given engine as it ages, or you may test different engines over the course of verification testing; however, you may not choose whether to repeat tests on a given engine at a later stage based on its measured emission levels. We generally require that you describe your plan for selecting engines in advance and justify any departures from that plan.
  - (2) Selected vehicles must come from independent sources, unless we approve your request to select vehicles that you own or manage. In your request, you must describe how you will ensure that the vehicle operator will drive in a way that represents normal in-use operation for the engine family.
  - (3) Select vehicles with installed engines from the same engine family and with the same power rating as the emission-data engine used to determine the deterioration factors. However, if the test engine does not have the specified power rating, you may ask for our approval to either test in the as-received condition or modify engines in selected vehicles by reflashing the ECM or replacing parts to change the engines to be in a different certified configuration for proper testing.
  - (4) Selected engines must meet the screening criteria described in [§ 1036.410(b)(2) through (4)](/cfr/40/1036.410.md?p=b-2..b-4). Selected engines must also have their original aftertreatment components and be in a certified configuration. You may ask us to approve replacing a critical emission-related component with an equivalent part that has undergone a comparable degree of aging.
  - (5) We may direct you to preferentially select certain types of vehicles, vehicles from certain model years. or vehicles within some range of service accumulation. We will not direct you to select vehicles that are 10 or more years old, or vehicles with an odometer reading exceeding 85 percent of the engine's useful life. We will specify a time frame for completing required testing.
- (b) Perform verification testing with one of the following procedures, or with an alternative procedure that you demonstrate to be equally effective:
  - (1) **Engine dynamometer testing.** Measure emissions from engines equipped with in-use aftertreatment systems on an engine dynamometer as follows:
    - (i) Test the aftertreatment system from at least two engines using the procedures specified in [subpart F](/cfr/40/subpartF.md) of this part and [40 CFR part 1065](/cfr/40/part1065.md). Install the aftertreatment system from the selected in-use vehicle, including all associated wiring, sensors, and related hardware and software, on one of the following partially complete engines:
      - (A) **The in-use engine from the same vehicle.**
      - (B) **The emission-data engine used to determine the deterioration factors.**
      - (C) A different emission-data engine from the same engine family that has been stablized as described in [40 CFR 1065.405(c)](/cfr/40/1065.405.md?p=c).
    - (ii) Perform testing on all certification duty cycles with brake-specific emission standards (g/hp·hr) to determine whether the engine meets all the duty-cycle emission standards, including any compliance allowance, for criteria pollutants. Apply infrequent regeneration adjustment factors as included in your application for certification or develop new factors if we request it.
    - (iii) **Evaluate verification testing for each pollutant independently.** You pass the verification test if at least 70 percent of tested engines meet standards for each pollutant over all duty cycles. You fail the verification test if fewer than 70 percent of engines meet standards for a given pollutant over all duty cycles.
  - (2) **PEMS testing.** Measure emissions using PEMS with in-use engines that remain installed in selected vehicles as follows:
    - (i) Test at least five engines using the procedures specified in [§ 1036.555](/cfr/40/1036.555.md) and [40 CFR part 1065](/cfr/40/part1065.md), subpart J.
    - (ii) Measure emissions of NOX, HC, and CO as the test vehicle's normal operator drives over a regular shift-day to determine whether the engine meets all the off-cycle emission standards that applied for the engine's original certification. Apply infrequent regeneration adjustment factors as included in your application for certification. For Spark-ignition HDE, calculate off-cycle emission standards for purposes of this subpart by multiplying the FTP duty-cycle standards in [§ 1036.104(a)](/cfr/40/1036.104.md?p=a) by 1.5 and rounding to the same number of decimal places.
    - (iii) **Evaluate verification testing for each pollutant independently.** You pass the verification test if at least 70 percent of tested engines meet the off-cycle standards including any compliance allowance and accuracy margin, for each pollutant. You fail the verification test if fewer than 70 percent of tested engines do not meet standards for a given pollutant.
    - (iv) You may reverse a fail determination under [paragraph (b)(2)(iii)](#b-2-iii) of this section by restarting and successfully completing the verification test for that year using the procedures specified in [paragraph (b)(1)](#b-1) of this section. If you do this, you must use the verification testing procedures specified in [paragraph (b)(1)](#b-1) of this section for all remaining verification testing for the engine family.
- (c) You may stop testing under the verification test program and concede a fail result before you meet all the testing requirements of this section.
- (d) **Prepare a report to describe your verification testing each year.** Include at least the following information:
  - (1) **Identify whether you tested using the procedures specified in paragraph (b)(1) or (2) of this section.**
  - (2) **Describe how the test results support a pass or fail decision for the verification test.** For in-field measurements, include continuous 1 Hz data collected over the shift-day and binned emission values determined under [§ 1036.530](/cfr/40/1036.530.md).
  - (3) If your testing included invalid test results, describe the reasons for invalidating the data. Give us the invalid test results if we ask for them.
  - (4) **Describe the types of vehicles selected for testing.** If you determined that any selected vehicles with enough mileage accumulation were not suitable for testing, describe why you chose not to test them.
  - (5) For each tested engine, identify the vehicle's VIN, the engine's serial number, the engine's power rating, and the odometer reading and the engine's lifetime operating hours at the start of testing (or engine removal).
  - (6) State that the tested engines have been properly maintained and used and describe any noteworthy aspects of each vehicle's maintenance history. Describe the steps you took to prepare the engines for testing.
  - (7) **For testing with engines that remain installed in vehicles, identify the date and location of testing.** Also describe the ambient conditions and the driving route over the course of the shift-day.
- (e) **Send electronic reports to the Designated Compliance Officer using an approved information format.** If you want to use a different format, send us a written request with justification.
  - (1) You may send us reports as you complete testing for an engine instead of waiting until you complete testing for all engines.
  - (2) We may ask you to send us less information in your reports than we specify in this section.
  - (3) We may require you to send us more information to evaluate whether your engine family meets the requirements of this part.
  - (4) Once you send us information under this section, you need not send that information again in later reports.
  - (5) We will review your test report to evaluate the results of the verification testing at each stage. We will notify you if we disagree with your conclusions, if we need additional information, or if you need to revise your testing plan for future testing.