What changed between these versions
A complete substitute amendment, v2 significantly revises the scope and conditions for diesel engine emissions relief. It removes the findings section, introduces a new definition for "agricultural equipment," and alters the temperature thresholds and conditions for temporary derate suspension. Crucially, v2 expands permanent derate suspension to agricultural equipment and broadens the type of relief for Arctic regions, while also removing the explicit waiver of emissions compliance during these relief periods.
Overview
Extensive changes throughout the bill, as v2 is a complete substitute amendment. · v2 restructures the bill, narrows the conditions for temporary cold weather relief, but expands permanent relief to a new category (agricultural equipment) and broadens the scope of permanent relief for Arctic regions, while also removing the explicit waiver of emissions compliance during relief periods.
The most significant change is the complete replacement of v1's text with a new version, including the removal of the "Findings" section and a shift in the bill's short title year. V2 introduces a new category of "agricultural equipment" eligible for permanent suspension of engine derate functions, and broadens the permanent relief for Arctic regions to cover all emissions control system triggers, not just DEF. However, it narrows the conditions for temporary cold weather derate suspension by requiring colder temperatures and removes the explicit waiver of emissions compliance during authorized suspension periods, which could create legal ambiguity.
Major additions
This new definition specifies "agricultural equipment" to include nonroad diesel equipment and machinery like tractors, combines, and other self-propelled equipment primarily designed for use in spraying, fertilizing, or harvesting covered commodities, as well as their engines. It explicitly excludes self-propelled machines for transportation on streets or highways.
The addition of this definition is highly significant as it creates a new, distinct category of vehicles and equipment that becomes eligible for permanent suspension of inducement-related engine derate or shutdown functions under Section 3(b)(1) of v2, which was not present in v1. This expands the scope of relief to the agricultural sector.
Deletions
This section contained four findings by Congress, stating the vital role of diesel vehicles in cold weather, the unreliability of diesel exhaust fluid (DEF) systems in prolonged freezing conditions, the life-threatening risks of automatic engine shutdowns, and that Clean Air Act safeguards were not intended to jeopardize human safety.
The deletion of the "Findings" section removes the explicit legislative intent and justification for the bill's provisions. While the operative sections still provide relief, the foundational rationale articulated by Congress is no longer part of the statutory text, potentially impacting future interpretation or challenges.
This provision granted a year-round exemption from diesel exhaust fluid system requirements for covered vehicles that encountered operational or logistical conditions characterized by prolonged ambient temperatures below the freezing point of diesel exhaust fluid or otherwise made the use of the DEF system impractical.
The removal of this provision significantly narrows the eligibility for relief for non-Arctic, non-agricultural vehicles. V1 allowed relief based on practical difficulties with DEF systems in cold conditions regardless of specific latitude, whereas v2 limits permanent relief only to agricultural equipment or vehicles operating north of 59 degrees north latitude. This means a broader range of vehicles previously eligible for DEF system exemptions based on local conditions are no longer covered.
Modifications
This is a minor, administrative change with no operative policy impact beyond updating the legislative session year.
Before
The short title of the Act was "Cold Weather Diesel Reliability Act of 2025".
After
The short title of the Act is "Cold Weather Diesel Reliability Act of 2026".
This modification narrows the conditions under which temporary derate/shutdown suspension is authorized, as it requires significantly colder temperatures (20F vs 32F). The removal of the "necessity" clause simplifies the activation criteria for manufacturers, potentially making it easier to implement when the temperature threshold is met, but only in more extreme cold.
Before
Authorized manufacturers to suspend derate/shutdown functions when ambient temperatures were at or below zero degrees Centigrade (32 F), subject to the engine returning to normal above 0C and the suspension being necessary to prevent occupational danger, equipment failure, or loss of essential transportation functionality in remote areas.
After
Authorizes manufacturers to suspend derate/shutdown functions when ambient temperatures are at or below 20 degrees Fahrenheit (-6.7 C), subject to the engine returning to normal above 20F. The condition regarding necessity to prevent danger/failure/loss of functionality is removed.
For vehicles operating north of 59 degrees north latitude, the relief is significantly expanded, as it now covers all emissions control system derate/shutdown triggers, not just those related to DEF. Agricultural equipment is now explicitly eligible for permanent suspension of these functions. However, vehicles in other cold regions that previously qualified based on practical difficulties with DEF systems are no longer eligible for this permanent relief, narrowing the geographic and operational scope for some.
Before
Granted a year-round exemption from diesel exhaust fluid (DEF) system requirements and associated derate/shutdown functions for vehicles primarily operated north of 59 degrees north latitude or those encountering prolonged freezing conditions making DEF use impractical.
After
Authorizes covered manufacturers to permanently suspend inducement-related engine derate or shutdown functions that are triggered by the emissions control system on agricultural equipment or a covered vehicle primarily operated north of 59 degrees north latitude.
This change creates significant legal ambiguity regarding the emissions performance of vehicles operating under the authorized suspensions. In v1, it was clear that during the specified relief periods, compliance with emissions standards was implicitly waived. In v2, by stating that compliance is never waived, it implies that even when derate/shutdown functions are suspended as authorized, the vehicle might still be considered non-compliant with emissions standards, potentially undermining the intended relief or exposing manufacturers/operators to liability.
Before
Stated that nothing in the Act waives compliance with emissions standards outside of the temporary cold-weather operational mode authorized under section 4(a) and the exemption from diesel exhaust fluid system requirements under section 4(b).
After
States that nothing in the Act waives compliance with any emissions standard under the Clean Air Act.
Scope
Complete substitute — Changes are scattered throughout the bill, affecting the short title, definitions, and both operative relief sections, as well as the rule of construction. — V2 represents a meaningful shift in policy direction. While maintaining the core intent of providing cold weather relief, it significantly alters the conditions for temporary relief, expands permanent relief to a new sector (agriculture) and broadens its scope for Arctic regions, but critically removes the explicit legal clarity regarding emissions compliance during authorized suspension periods. — The changes to the definitions (adding "agricultural equipment") directly interact with and enable new operative provisions in Section 3(b). The modification to the Rule of Construction in Section 4 has a broad interaction, potentially affecting the legal interpretation and effectiveness of all relief provisions in Section 3 by removing the explicit waiver of emissions compliance during those periods.
Impact analysis
Manufacturers of covered vehicles and engines
Mixed. Gains expanded authority for certain permanent suspensions, but faces narrower conditions for temporary relief and increased legal ambiguity regarding emissions compliance during all suspension periods.
They are now authorized to permanently suspend derate/shutdown functions for agricultural equipment and have broader authority for Arctic vehicles, but the temporary cold weather suspension is only allowed at colder temperatures. The removal of the "necessity" clause for temporary suspension simplifies implementation.
Operators of agricultural equipment
Gains significant relief, allowing for uninterrupted operation of essential equipment.
These operators are now explicitly eligible for permanent suspension of inducement-related engine derate or shutdown functions triggered by the emissions control system. This was not a specific category for relief in v1.
Operators of covered vehicles primarily operated north of 59 degrees north latitude
Gains significantly broader and more comprehensive relief, enhancing reliability in extreme cold.
The scope of relief for these operators is expanded from an exemption for DEF system requirements and DEF-triggered derate/shutdowns to a permanent suspension of all inducement-related engine derate or shutdown functions triggered by the emissions control system.
Operators of non-agricultural, non-Arctic covered vehicles in regions with prolonged freezing conditions
Loses a previously available exemption, potentially facing increased operational challenges due to DEF system issues in cold weather.
V1 allowed these vehicles to receive a year-round exemption from DEF system requirements if operational or logistical conditions made DEF use impractical. This provision has been deleted in v2.
All operators of covered vehicles (including those eligible for relief)
Experiences increased legal ambiguity and potential risk regarding emissions compliance during periods of authorized derate/shutdown suspension.
The removal of the explicit waiver of emissions compliance during authorized suspension periods in the Rule of Construction introduces legal uncertainty. While derate/shutdown functions are suspended, the vehicles may still be considered non-compliant with emissions standards.