1997 to Present Manufacturers Advisory Correspondence (MAC) - Mobile Source Emissions Certification Guidelines
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Last Updated - January 22, 2025.
Manufacturer Advisory Correspondence (MAC) letters: 2025
Document # | Description / Attachments |
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MAC ECCD-2025-01 | Guidance for Model Year 2024 and 2025 Small Off-Road Engines |
Manufacturer Advisory Correspondence (MAC) letters: 2024
Document # | Description / Attachments |
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Clarification of Certification Requirements for 2024 through 2026 Model Year Legacy Engines | |
MAC ECCD-2024-03 | Certification Fees for New 2026 Model Year (MY) Light-Duty Vehicle Test Groups, Medium-Duty Vehicle Test Groups, Heavy-Duty Engine Families, Medium-Duty Engine Families, Heavy-Duty Vehicle Evaporative Emissions Families, Incomplete Medium-Duty Vehicle Evaporative Emissions Families, Heavy-Duty Greenhouse Gas Vehicle Families and Trailer Families, Street-use Motorcycle Families and Motorcycle Engine Families, On-Road Heavy-Duty Exempt Engines and Certification Fees for New 2025 Calendar Year (CY) Zero-Emission Powertrain Families, Aerodynamic Technologies, and Fuel-Fired Heaters |
MAC ECCD-2024-001 | Cost Limit for High‑Priced Warranted Parts for New 2025 Model‑Year (MY) Passenger Cars (PC), Light‑Duty Trucks (LDT), Medium‑Duty Vehicles and Engines Used in These Vehicles (MDV/E), Engine Packages for Use in Light‑Duty Specially Constructed Vehicles (SPCN), Engine Packages for Use in Light‑Duty Specially‑Produced Motor Vehicles (SPMV), Off‑Road Large Spark‑Ignition Engines (LSIE), Off‑Highway Recreational Vehicles (OHRV), and Alternative Fuel Retrofit (AFR) Systems Certified During Calendar Years (CY) 2024 and 2025 for Installation on In‑Use MY 1994 and Subsequent On‑Road Vehicles and Engines (ONR Vehicle/Engine) Including PC, LDT, MDV/E and Heavy‑Duty Engines and Vehicles Equipped with These Engines (HDE/V) |
Manufacturer Advisory Correspondence (MAC) letters: 2023
Document # | Description / Attachments |
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MAC 23-01 | Spark-Ignition Marine Watercraft Evaporative Regulatory Clarification and Certification Requirements for 2024MY and Subsequent Spark-Ignition Marine Watercraft (SIMW) and Spark-Ignition Marine Engines (SIME) |
MAC 23-02 | Optional Electronic Warranty Booklets Requirements |
MAC 23-03 | Over-the-Air Recall Requirements |
MAC ECCD-2023-04 | Cost Limit for High‑Priced Warranted Parts for New 2024 Model‑Year (MY) Passenger Cars (PC), Light‑Duty Trucks (LDT), Medium‑Duty Vehicles and Engines Used in These Vehicles (MDV/E), Engine Packages for Use in Light‑Duty Specially Constructed Vehicles (SPCN), Engine Packages for Use in Light‑Duty Specially‑Produced Motor Vehicles (SPMV), Off‑Road Large Spark‑Ignition Engines (LSIE), Off‑Highway Recreational Vehicles (OHRV), and Alternative Fuel Retrofit (AFR) Systems Certified During Calendar Years (CY) 2023 and 2024 for Installation on In‑Use MY 1994 and Subsequent On‑Road Vehicles and Engines (ONR Vehicle/Engine) Including PC, LDT, MDV/E and Heavy‑Duty Engines and Vehicles Equipped with These Engines (HDE/V) |
Manufacturer Advisory Correspondence (MAC) letters: 2022
Document # | Description / Attachments |
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MAC 22-01 | California Phase 2 GHG regulation A/C leakage requirements for 2021 and subsequent model year medium- and heavy-duty vehicles whose A/C system installation involves both a certifying vehicle manufacturer and one or more non-certifying secondary vehicle manufacturers.
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MAC 22-03 | Cost Limit for High‑Priced Warranted Parts for New 2023 Model‑Year (MY) Passenger Cars (PC), Light‑Duty Trucks (LDT), Medium‑Duty Vehicles and Engines Used in These Vehicles (MDV/E), Engine Packages for Use in Light‑Duty Specially Constructed Vehicles (SPCN), Engine Packages for Use in Light‑Duty Specially‑Produced Motor Vehicles (SPMV), Off‑Road Large Spark‑Ignition Engines (LSIE), Off‑Highway Recreational Vehicles (OHRV), and Alternative Fuel Retrofit (AFR) Systems Certified During Calendar Years (CY) 2022 and 2023 for Installation on In‑Use MY 1994 and Subsequent On‑Road Vehicles and Engines (ONR Vehicle/Engine) Including PC, LDT, MDV/E and Heavy‑Duty Engines and Vehicles Equipped with These Engines (HDE/V) |
MAC 22-04 | Clean Idle Label (CIL) for 2024 and 2025 MY HDDEs Defined as Legacy Engines and 2024 through 2026 MY HDDEs at or above 525 Brake-horsepower Maximum Power |
Manufacturer Advisory Correspondence (MAC) letters: 2021
Document # | Description / Attachments |
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MAC 21‑01 | Cost Limit for High‑Priced Warranted Parts for New 2022 Model‑Year (MY) Passenger Cars (PC), Light‑Duty Trucks (LDT), Medium‑Duty Vehicles and Engines Used in These Vehicles (MDV/E), Engine Packages for Use in Light‑Duty Specially Constructed Vehicles (SPCN), Engine Packages for Use in Light‑Duty Specially‑Produced Motor Vehicles (SPMV), Off‑Road Large Spark‑Ignition Engines (LSIE), Off‑Highway Recreational Vehicles (OHRV), and Alternative Fuel Retrofit (AFR) Systems Certified During Calendar Years (CY) 2021 and 2022 for Installation on In‑Use MY 1994 and Subsequent On‑Road Vehicles and Engines (ONR Vehicle/Engine) Including PC, LDT, MDV/E and Heavy‑Duty Engines and Vehicles Equipped with These Engines (HDE/V) |
Manufacturer Advisory Correspondence (MAC) letters: 2020
Document # | Description / Attachments |
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MAC 20‑02 | Certification Guidance for California Phase 2 Greenhouse Gas (GHG) Regulations for Medium‑ and Heavy‑Duty Engines, Vehicles, and Trailers |
Manufacturer Advisory Correspondence (MAC) letters: 2019
Document # | Description / Attachments |
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MAC 2019‑01 | Cost Limit For High‑Priced Warranted Parts For 2020 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), Off‑Road Large Spark‑Ignition Engines (LSIEs), Off‑Highway Recreational Vehicles (OHRVs), and Alternative Fuel Retrofit Systems Certified During Calendar Year (CY) 2019 And CY 2020 Installed In On‑Road PCs, LDTs, MDVs And Heavy‑Duty Vehicles. |
MAC 2019‑02 | Environmental Performance Label Requirements For Medium‑Duty Vehicle Manufacturers On And After January 1, 2021.Attachment 2: Template For Requesting GHG And Smog Ratings Approval. |
Manufacturer Advisory Correspondence (MAC) letters: 2018
Document # | Description / Attachments |
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MAC 2018‑01 | Cost Limit For High‑Priced Warranted Parts For 2019 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), Off‑Road Large Spark‑Ignition Engines (LSIEs), Off‑Highway Recreational Vehicles (OHRVs), and Alternative Fuel Retrofit Systems Certified During Calendar Year (CY) 2018 And CY 2019 Installed In On‑Road PCs, LDTs, MDVs And Heavy‑Duty Vehicles. |
Manufacturer Advisory Correspondence (MAC) letters: 2017
Document # | Description / Attachments |
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MAC 17‑01 | Clarification of the Emission Warranty Information Report (EWIR) formatting requirements used for 1990 and Subsequent Model Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) and Engines Used in These Vehicles (MDEs), Heavy‑Duty Vehicles (HDVs) and Engines used in These Vehicles (HDEs), and Motorcycles |
MAC 17‑02 | Heavy‑Duty In‑Use Testing (HDIUT) Data Drift Validation Handling Process |
MAC 2017‑03 | Cost Limit For High‑Priced Warranted Parts For 2018 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), Off‑Road Large Spark‑Ignition Engines (LSIEs), Off‑Highway Recreational Vehicles (OHRVs), and Alternative Fuel Retrofit Systems Certified During Calendar Year (CY) 2017 And CY 2018 Installed In On‑Road PCs, LDTs, MDVs And Heavy‑Duty Vehicles. |
Manufacturer Advisory Correspondence (MAC) letters: 2016
Document # | Description / Attachments |
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MAC 16‑01 | Cost Limit For High‑Priced Warranted Parts For 2017 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs), and Alternative Fuel Retrofit Systems Certified During Calendar Year (CY) 2016 And CY 2017 Installed In On‑Road PCs, LDTs, MDVs And Heavy‑Duty Vehicles. |
Manufacturer Advisory Correspondence (MAC) letters: 2015
Document # | Description / Attachments |
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MAC 15‑01 | Cost Limit For High‑Priced Warranted Parts For 2016 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs), and Alternative Fuel Retrofit Systems Certified During Calendar Year (CY) 2015 And CY 2016 Installed In On‑Road PCs, LDTs, MDVs And Heavy‑Duty Vehicles. |
Manufacturer Advisory Correspondence (MAC) letters: 2014
Document # | Description / Attachments |
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MAC 14‑01 | Cost Limit For High‑Priced Warranted Parts For 2015 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs), and Alternative Fuel Retrofit Systems Certified During Calendar Year (CY) 2014 And CY 2015 Installed In On‑Road PCs, LDTs, MDVs And Heavy‑Duty Vehicles. |
Manufacturer Advisory Correspondence (MAC) letters: 2013
Document # | Description / Attachments |
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MAC 13‑01 | Cost Limit For High‑Priced Warranted Parts For 2014 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 13‑02 | Clarification Of The Emission Warranty Information Report (EWIR) Formatting Requirements Currently Used For 2010 And Subsequent Model Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs), And Engines Used In These Vehicles (MDEs), Heavy‑Duty Vehicles (HDVs) And Engines Used In These Vehicles (HDEs), And Motorcycles. |
Manufacturer Advisory Correspondence (MAC) letters: 2012
Document # | Description / Attachments |
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MAC 12‑01 | Cost Limit For High‑Priced Warranted Parts For 2013 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
Manufacturer Advisory Correspondence (MAC) letters: 2011
Document # | Description / Attachments |
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MAC 11‑03 | Cost Limit For High‑Priced Warranted Parts For 2012 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
Manufacturer Advisory Correspondence (MAC) letters: 2010
Document # | Description / Attachments |
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MAC 10‑01 | Cost Limit For High‑Priced Warranted Parts For 2011 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 10‑02 | Clarification of Alternate NOx Family Emission Level for 2011‑2014 Model Year Nonroad Compression Ignition Engines in the 130 = kW = 560 Power Category (PDF ‑ 36K) |
Manufacturer Advisory Correspondence (MAC) letters: 2009
Document # | Description / Attachments |
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MAC 09‑01 | Implementation of New Environmental Performance Label (PDF ‑ 140K)Attachment: Test Group Information Format |
MAC 09‑02 | Cost Limit For High‑Priced Warranted Parts For 2010 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 09‑03 | Determination for Manufacturers of Passenger Cars (PC), Light‑Duty Trucks (LDT) and Medium‑Duty Passenger Vehicles (MDPV) Subject to California's Greenhouse Gas (GHG) Emission Fleet Average Requirement
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Manufacturer Advisory Correspondence (MAC) letters: 2008
Document # | Description / Attachments |
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MAC 08‑01 | Cost Limit For High‑Priced Warranted Parts For 2009 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 08‑02 | Amendments to the Emission Warranty Information Report (EWIR) for 2010 and Subsequent Model Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) and Engines Used in These Vehicles (MDEs), And Heavy‑Duty Vehicles (HDVs), Engines Used in These Vehicles (HDEs), and Motorcycles |
Manufacturer Advisory Correspondence (MAC) letters: 2007
Document # | Description / Attachments |
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MAC 07‑01 | Policy regarding the use of Electronic Signatures in the Air Resources Board's (ARB) Document Management System for Certification |
MAC 07‑02 | Cost Limit For High‑Priced Warranted Parts For 2008 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 07‑03 | Protocol for the Engine Shutdown System on New California Certified Heavy‑Duty Diesel Engines for 2008 and Subsequent Model Years |
MAC 2007‑03 | Protocol for the Engine Shutdown System on New California Certified Heavy‑Duty Diesel Engines for 2008 and Subsequent Model Years |
Manufacturer Advisory Correspondence (MAC) letters: 2006
Document # | Description / Attachments |
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MAC 06‑01 | Cost Limit For High‑Priced Warranted Parts For 2007 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 06‑02 | Cover Letter MAC 06‑02: "Fast Refueling Capability" Criterion for 2003 and Subsequent Model‑Year Type III Zero‑Emission Vehicles (ZEV) and Information Requested for Advanced Technology Demonstration Applications. |
MAC 06‑03 | MAC 06‑03: Zero‑Emission Vehicle (ZEV) Credit Reporting and Tracking System
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Manufacturer Advisory Correspondence (MAC) letters: 2005
Document # | Description / Attachments |
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MAC 05‑02 | Cost Limit For High‑Priced Warranted Parts For 2006 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) And Engines Used In These Vehicles (MDEs), And Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 05‑01 | Interim Voluntary Low Emission Standards for New Model Year (MY) 2005 and 2006 Off‑Road Large Spark‑Ignition (LSI) Engines |
MAC 05‑03 | Optional Test Procedure For Certifying 2008 and Later Model‑Year Gasoline‑Fueled Zero‑Fuel Evaporative Vehicles |
MAC 05‑05 | Evaporative Emission Requirements for Vehicles with On‑Board Generators |
Manufacturer Advisory Correspondence (MAC) letters: 2004
Document # | Description / Attachments |
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MAC 04‑01 | Zero‑Emission Vehicle (ZEV) Credit Reporting and Tracking System
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MAC 04‑02 | Evaporative Testing Requirements for Dual‑Fuel Compressed Natural Gas (CNG) / Gasoline and Liquefied Petroleum Gas (LPG) / Gasoline Vehicles Revision of MAC #99‑01 to Allow Subtraction of Methane Emissions from CNG / Gasoline Dual‑Fuel Vehicles (DFVs) |
MAC 04‑03 | Cost Limit for High‑Priced Warranted Parts of 2005 Model Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), Medium‑Duty Vehicles (MDVs) and Engines Used in These Vehicles (MDEs), and Off‑Road Large Spark‑Ignition Engines (LSIEs) |
MAC 04‑04 | Optional Duarability Demonstration and Certification Procedure for New 2002‑2006 Model Year Diesel, Diesel Dual‑Fuel and Diesel Bi‑Fuel Urban Bus Engines Produced On or After October 1, 2002 Meeting New 0.01 g/bhp‑hr Particulate (PM) and/or 0.5 g/bhp‑hr Oxides of Nitrogen (NOx) Standards Using a Verfied Diesel PM or NOx Aftertreatment System |
Manufacturer Advisory Correspondence (MAC) letters: 2003
Document # | Description / Attachments |
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MAC 03‑01 | Hang Tag and Star Labels for 2003 and Later Model Year Spark‑Ignition Marine Engines |
MAC 03‑02 | Guidance to Certification and Compliance with California's Supplemental Test Procedures, Including, and Specific to, Not‑To‑Exceed (NTE) Emission Tesing Caps for 2005 and 2006 Model Year (MY) Heavy‑Duty and Medium‑Duty Diesel Engines (HDDEs and MDDEs) |
MAC 03‑03 | Cost Limit for High‑Priced Warranted Parts of 2004 Model Year (MY) Passenger Cars (PC), Light‑Duty Trucks (LDT), Medium‑Duty Vehicles (MDV) and Engines Used in These Vehicles (MDE), and Off‑Road Large Spark‑Ignition Engines (LSIE) |
Manufacturer Advisory Correspondence (MAC) letters: 2002
Document # | Description / Attachments |
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MAC 02‑01 | Cost Limit for High‑Priced Warranted Parts on 2003 Model Year Passenger Cars (PC), Light‑Duty Trucks (LDT), and Medium‑Duty Vehicles (MDV) |
MAC 02‑02 | Use of Bag Mini‑Diluter Sampling Systems in Lieu of Constant Volume Sampling for Mass Emissions Testing |
Manufacturer Advisory Correspondence (MAC) letters: 2001
Document # | Description / Attachments |
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MAC 01‑01 | Optional Use of the Federal Engine Test Cycle Speed and Load Specifications for Exhaust Emission Testing of Spark‑Ignition Small Off‑Road Engines |
MAC 01‑02 | Cost Limit for High‑Priced Warranted Parts of 2002 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), and Medium‑Duty Vehicles (MDVs) |
MAC 01‑03 | Optional Test Procedure For Certifying Pre‑2005 Model Year Gasoline‑Fueled Zero‑Evaporative Vehicles and For Offsetting Evaporative And NMOG Emissions For Such Vehicles |
Manufacturer Advisory Correspondence (MAC) letters: 2000
Document # | Description / Attachments |
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MAC 00‑01 | Required Format for Manufacturer Quarterly Audit Reports for 2000 Model Year Passenger Cars (PCs), Light‑Duty Trucks and Medium‑Duty Vehicle Engine Families Certifying to Compliance Assurance Program (CAP 2000) Regulations |
MAC 00‑02 | Cost Limit for High‑Priced Warranted Parts of 2001 Model‑Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), and Medium‑Duty Vehicles (MDVs) |
MAC 00‑03 | Format for Manufacturer Quarterly Assembly‑Line Production Reports for 2001 and Subsequent Model Year Passenger Cars, Light‑Duty Trucks and Medium‑Duty Vehicles Including Full / Partial Zero‑Emission Vehicles Attachment ‑ (Excel ‑ 43K) |
Manufacturer Advisory Correspondence (MAC) letters: 1999
Document # | Description / Attachments |
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MAC 1999‑04 | Tamper‑Resistance Requirements for Diesel Injection Pumps |
MAC 99‑01 | Evaporative Testing Requirements for Dual‑Fueled CNG / Gasoline and LPG / Gasoline Vehicles |
MAC 99‑02 | Cost Limit for High‑Priced Warranted Parts of 2000 Model Year (MY) Passenger Cars (PCs), Light‑Duty Trucks (LDTs), and Medium‑Duty Vehicles (MDVs) |
MAC 99‑05 | Certification Compliance With the Acceleration Simulation Mode (ASM) Loaded‑Mode Inspection and Maintenance (I/M) Standards |
MAC 99‑06 | Certification of Direct Ozone Reduction Technologies |
Manufacturer Advisory Correspondence (MAC) letters: 1998
Document # | Description / Attachments |
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MAC 98‑02 | Cost Limit for High‑Priced Warranted Parts of 1999 Model‑Year Passengers Cars, Light‑Duty Trucks, and Medium‑Duty Vehicles |
MAC 98‑03 | ARB's Reporting Requirements for Experimental Permits Issued for Fleets of Vehicles and Engines |
MAC 98‑04 | Vehicle Manufacturers Must Submit Demonstrations of Compliance with California's Inspection and Maintenance Program |
Manufacturer Advisory Correspondence (MAC) letters: 1997
Document # | Description / Attachments |
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MAC 97‑01 | Assigned Deterioration Factors for Vehicles Certified to the Useful Life and Running Loss (Enhanced) Evaporative Emission Standards |
MAC 97‑02 | Cost Limit for High‑Priced Warranted Parts of 1998 Model‑Year Passengers Cars, Light‑Duty Trucks, and Medium‑Duty Vehicles |
MAC 97‑03 | Required Format for Submitting Manufacturer Quality Audit Quarterly Assembly‑Line Reports Electronically and in Hard Copy |