US SB3135

Requires EPA within 180 days to revise Clean Air Act regulations allowing diesel vehicle manufacturers to suspend engine derate or shutdown functions triggered by emissions control system faults when temperatures are at or below 0°C (32°F)

Engines must return to normal emission control operation once temperatures rise above 0°C, and the suspension only applies when continued performance is necessary to prevent danger, equipment failure, or loss of transportation in remote areas

Grants year-round exemption from diesel exhaust fluid (DEF) system requirements for vehicles primarily operated north of 59° north latitude (covering most of Alaska) or in conditions where DEF systems are impractical due to prolonged freezing

Exempted vehicles are not required to have engine derate or shutdown functions triggered by DEF system absence, malfunction, or faults

Maintains compliance with all other Clean Air Act emissions standards outside of the temporary cold-weather operational mode and DEF system exemptions