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  2. Verified Technologies for SmartWay and Clean Diesel
  3. Clean Diesel Technology

Verified Technologies List for Clean Diesel

  • Learn about
  • Verified list
  • Formerly Verified List
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Help
Air pollutants:
  • PM (Particulate Matter).
    For more information, go to: Particulate Matter (PM) Basics
  • NO2 (Nitrogen Dioxide, part of group of gases called nitrogen oxides or NOx).
    For more information, go to: Nitrogen Dioxide (NO2) Pollution
  • HC (Hydrocarbon).
    For more information, go to: Total Petroleum Hydrocarbons
  • CO (Carbon monoxide).
    For more information, go to: Basic Information about CO Outdoor Air Pollution
For help on using the table below:
  • View Table Instructions

The list below provides information about diesel retrofit technologies that EPA has approved or conditionally approved for use in engine retrofit programs. It also shows the percent reduction (of verified or tested levels) that EPA will recognize for emission reductions for each technology.

Searchable/Sortable Table Instructions

The table default is to show 10 table entries at a time. To change the number of entries shown, click the drop-down arrow next to the number.
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The column with the blue arrow indicates which column your table is sorted by. For example, if you saw the image below, the table would be sorted in ascending order on the "Technology Type" column.
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To change which column your table is sorted by, click an arrow in another column. For example, if you wanted to sort by descending order on the "Applicable for" column in the image below, you would click the down arrow.
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IMPORTANT NOTES:
  • Please read: EPA's Disclaimer on Verified Technologies
  • Click the technology link to learn more about the retrofit technology and its operating criteria.
Manufacturer Technology Applicability PM Reduction NOx Reduction HC Reduction CO Reduction
BASF
(formerly listed under Engelhard)
CMX Catalyst Muffler Highway, heavy-duty, 4 cycle engines 20% n/a 50% 40%
Caterpillar, Inc. Caterpillar Locomotive Selective Catalytic Reduction (SCR) System Caterpillar 3516, line-haul locomotive engines; either originally manufactured to meet Tier 2 standards for model years 2010–2011, remanufactured to meet Tier 1 standards for model years 2012–2013, or remanufactured to meet Tier 2 standards for model year 2016; turbocharged with power ratings 2650 ≤ Horsepower ≤ 3005 when used in line-haul application/duty cycle only 20% 75% 90% 70%
Caterpillar, Inc. Converter GP-Catalytic Technology (CGP) system Non-road, Certain M313D and M315D Caterpillar wheeled hydraulic excavators equipped with models 313 and 315 for Tier 3 engines from families: CPKXL04.4NH1, CPKXL04.4NJ2, CPKXL04.4NJ1, or CPKXL04.4NL1. 95% 15% 95% 95%
Caterpillar, Inc. Diesel Particulate Filter (DPF) Nonroad, 4 cycle, non-EGR equipped, model year 1996-2005, turbocharged engines with power ratings 130 ≤ KiloWatts < 225 (174.2 ≤ Horsepower < 301.5) 89% n/a 93% 90%
Caterpillar, Inc. Emissions Upgrade Group (model 3306) Caterpillar model 3306 diesel engines for nonroad applications with model years from 1970 to 1995 with mechanical direct fuel injection 22% 37% 71% 13%
Caterpillar, Inc. Emissions Upgrade Group (model 3406) Caterpillar model 3406 diesel engines for nonroad applications with model years from 1973 to 1995 with mechanical fuel injection 0.54g/kW-hr
(Nonroad Tier 1 Level)
9.2g/kW-hr
(Nonroad Tier 1 Level)
1.3g/kW-hr
(Nonroad Tier 1 Level)
11.4g/kW-hr
(Nonroad Tier 1 Level)
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #1 (MUI to EUI) Caterpillar 3512 diesel engines for non-road, marine applications, model year 1994 – 2006 with mechanical direct fuel injection 35% 35% 18% 60%
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #2 (MUI to Tier 1) Caterpillar 3508, 3512, and 3516 (large cam bore) diesel engines for non-road, marine applications, model year 1994 – 2006 45% 10.05g/kW-hr
(Marine Diesel Engine Tier 1 Level)
28% 65%
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #3 (MUI to Tier 2) Caterpillar 3508, 3512, and 3516 (large cam bore) diesel engines for non-road, marine applications, model year 1994 – 2006 0.27g/kW-hr
(Marine Tier 2 Level)
7.8g/kW-hr
(Marine Tier 2 Level)
7.8g/kW-hr
(Marine Tier 2 Level)
5.0g/kW-hr
(Marine Tier 2 Level)
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #4 (EUI to Tier 1) Caterpillar 3508, 3512, and 3516 (large cam bore) diesel engines for non-road, marine applications, model year 1994 – 2006, originally equipped with electronic unit injection (EUI) and rated at 1600 or 1800 rpm n/a 10.05g/kW-hr
(Marine Diesel Engine Tier 1 Level)
n/a n/a
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #5 (EUI to Tier 2) Caterpillar 3508, 3512, and 3516 (large cam bore) diesel engines for non-road, marine applications, model year 1994 – 2006, originally equipped with electronic unit injection (EUI) and rated at 1600 rpm 0.27g/kW-hr
(Marine Tier 2 Level)
7.8g/kW-hr
(Marine Tier 2 Level)
7.8g/kW-hr
(Marine Tier 2 Level)
5.0g/kW-hr
(Marine Tier 2 Level)
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #6 (Tier 1 to Tier 2) Caterpillar 3508, 3512, and 3516 (large cam bore) diesel engines for non-road, marine applications, model year 1994 – 2006, Tier 1 engine and rated at 1200, 1600, or 1800 rpm (varies by model) 0.27g/kW-hr
(Marine Tier 2 Level)
7.8g/kW-hr
(Marine Tier 2 Level)
7.8g/kW-hr
(Marine Tier 2 Level)
5.0g/kW-hr
(Marine Tier 2 Level)
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #7 (Tier 2 to Tier 3)

Caterpillar 3512 and 3516 (large cam bore) diesel engines for nonroad, marine applications, model year 1994 and newer, originally equipped with Tier 2 engines and rated at 1600 or 1800 rpm (varies by model)

0.11g/kW-hr
(Marine Tier 3 Level)
5.8g/kW-hr
(Marine Tier 3 Level NOx+HC)
n/a 5.0g/kW-hr
(Marine Tier 3 Level)
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #8 (Tier 1 to Tier 3)

Caterpillar 3512 and 3516 (large cam bore) diesel engines for nonroad, marine applications, model year 1994 and newer, originally equipped with Tier 1 engines and rated at 1600 or 1800 rpm (varies by model)

0.11g/kW-hr
(Marine Tier 3 Level)
5.8g/kW-hr
(Marine Tier 3 Level NOx+HC)
n/a 5.0g/kW-hr
(Marine Tier 3 Level)
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #9 (EUI to Tier 3)

Caterpillar 3512 and 3516 (large cam bore) diesel engines for nonroad, marine applications, model year 1994 and newer, originally equipped with electronic unit injectors (EUI) and rated at 1600 or 1800 rpm (varies by model)

0.11g/kW-hr
(Marine Tier 3 Level)
5.8g/kW-hr
(Marine Tier 3 Level NOx+HC)
n/a 5.0g/kW-hr
(Marine Tier 3 Level)
Caterpillar, Inc. Marine Engine Emissions Upgrade Group Kit #10 (MUI to Tier 3)

Caterpillar 3512 and 3516 (large cam bore) diesel engines for nonroad, marine applications, model year 1994 and newer, originally equipped with mechanical unit injectors (MUI)and rated at 1600 or 1800 rpm (varies by model)

0.11g/kW-hr
(Marine Tier 3 Level)
5.8g/kW-hr
(Marine Tier 3 Level NOx+HC)
n/a 5.0g/kW-hr
(Marine Tier 3 Level)
Clean Diesel Group LLC

Low Nitrogen
Dioxide Filter (LNF)

Highway model year 1993 through 2006 and have an engine family name listed in the Attachment A 90% n/a 90% 80%
Clean Diesel Group LLC Low Oxides of Nitrogen Filter (LXF) Highway model year 2002 through 2006 and have an engine family name listed in the Attachment A 90% n/a 90% 90%
Clean Diesel Technologies, Inc. (CDTi)
(formerly Engine Control Systems Limited)
AZC Purimuffler or AZC Purifier Diesel Oxidation Catalyst (DOC) Highway, heavy-duty, 4 cycle engines 1991 through 2006 20% n/a 50% 50%
Clean Diesel Technologies, Inc. (CDTi)
(formerly Engine Control Systems Limited)
AZC Purimuffler or AZC Purifier Diesel Oxidation Catalyst (DOC) plus CDTi Closed Crankcase Ventilation (CCV) System Highway, heavy-duty, mechanically or electronically injected, turbocharged or naturally aspirated, originally manufactured from 1991 through 2006 model years which meet a 5 or 4 g/bhp-hr NOx standard 25% n/a 50% 50%
Clean Diesel Technologies, Inc. (CDTi)
(formerly Engine Control Systems Limited)
Purifilter - Diesel Particulate Filter (DPF) Environmental Technology Verification Logo Highway, heavy and medium heavy-duty; Urban Bus; 4-cycle; model years 1994 - 2003; turbocharged or naturally aspirated; non-EGR engines 90% n/a 85% 75%
Clean Diesel Technologies, Inc. (CDTi)
(formerly Engine Control Systems Limited)
Purifilter EGR Diesel Particulate Filter (DPF) Highway; light, medium and heavy-heavy duty engines (EGR and non-EGR) certified in model years 1993-2010 90% n/a 90% 80%
Clean Diesel Technologies, Inc. (CDTi)
(formerly Engine Control Systems Limited)
Purifilter OR Diesel Particulate Filter (DPF) for Non-Road Applications System Nonroad, Tier 1 or Tier 2 or Tier 3 diesel engines certified with a maximum PM level of 0.20 g/bhp-hr with power ratings 100 ≤ Horsepower ≤ 603hp 90% n/a 90% 85%
Clean Diesel Technologies, Inc. (CDTi)
(formerly Engine Control Systems Limited)
Purifilter Plus - Diesel particulate filter (DPF) Highway; heavy, medium, and light heavy-duty; Urban Bus; 4-cycle; model years 1994 - 2006; turbocharged or naturally aspirated; non-EGR engines 90% n/a 85% 75%
Clean Diesel Technologies, Inc. (CDTi)
(formerly Engine Control Systems Limited)
Purifilter Plus M - Diesel Particulate Filter (DPF) Highway; light, medium, and heavy-heavy duty EGR and non-EGR engines, not originally certified or equipped with DPF, originally manufactured from 1994-2010 90% n/a

0%
(for DOC equipped engines)

or 70%
(for non-DOC equipped engines)

75%
Clean Diesel Group, LLC Semi-Active Electric Diesel Particulate Filter (SEF) System On-road, 4-stroke diesel engines, turbocharged or naturally aspirated for engines rated ≤400 hp, originally manufactured from model year 1991-2006, and engine family name listed in the Attachment A 90% n/a 65% 60%
Clean Diesel Group LLC (previously verified by Donaldson) Semi-Active Electric Filter for Non-Road Applications (NR-SEF) System Nonroad, model year 1996-2010, with power rating between 100 and 400 hp and particulate matter (PM) certification levels less than 0.25 g/bhp-hr 90% n/a 95% 90%
Clean Diesel Group LLC (previously verified by Donaldson) Low NO2 Diesel Particulate Filter for Non-Road Applications (NR-LNF DPF) System Non-road, Tier 1 or Tier 2 diesel engines certified with a maximum PM level of 0.25 g/bhp-hr with power rating 75 ≤ Kilowatts < 450 (100.6 ≤ Horsepower < 603.4) 90% n/a 95% 90%
Clean Diesel Group LLC (previously verified by Donaldson) Series 6000 Diesel Oxidation Catalyst (DOC) & Spiracle Closed Crankcase Filtration system Highway, heavy-heavy and medium heavy-duty, 4-cycle, non-EGR, model year 1991 - 2003, turbocharged or naturally aspirated engines 25 to 33% n/a 50 to 52% 13 to 23%
Donaldson Series 6100 Diesel Oxidation Catalyst (DOC) Highway, heavy-heavy and medium heavy-duty, 4-cycle, non-EGR, model year 1991 - 2003, turbocharged or naturally aspirated engines 20 to 26% n/a 49 to 66% 38 to 41%
Clean Diesel Group LLC (previously verified by Donaldson)   Series 6100 Diesel Oxidation Catalyst (DOC) & Spiracle Closed Crankcase Filtration system Highway, heavy-heavy and medium heavy-duty, 4-cycle, non-EGR, model year 1991 - 2003, turbocharged or naturally aspirated engines 28 to 32% n/a 42% 31 to 34%
Clean Diesel Group LLC (previously verified by Donaldson) Series 6400 Diesel Oxidation Catalyst (DOC) & Spiracle Closed Crankcase Filtration system Highway, heavy-heavy and medium-heavy duty, 4 cycle, non-EGR, model year 1991 - 2003, turbocharged or naturally aspirated engines 28% n/a 50% 23%
Foss Maritime / AKA XeroPoint Hybrid Tugboat Retrofit System Harbor tugboat vessels with auxiliary generator engines with rated horsepower range between 100 and 750 hp and main propulsion engines up to 5,000 hp each 25% 30% 15% 35%
Johnson Matthey Advanced Catalyzed Continuously Regenerating Technology (AdvCCRT) System Highway, 4-cycle; light-, medium-, and heavy- heavy duty diesel engines including turbo-charged or naturally aspirated, EGR and non-EGR, and originally manufactured from 2002 through 2006 model years 90% n/a n/a 50%
Johnson Matthey CEM™ Catalytic Exhaust Muffler and/or DCC™ Catalytic Converter Highway, heavy- duty, non-urban bus, 4-cycle, EGR equipped model year 2003, EGR and non-EGR model year 2004 – 2006 turbocharged or naturally aspirated diesel engines certified without a diesel oxidation catalyst 20% n/a 50% 40%
Johnson Matthey CEM™ Catalytic Exhaust Muffler and/or DCC™ Catalytic Converter Highway, heavy- duty, non-urban bus, 4-cycle, non-EGR, model year 1988 – 1997 turbocharged or naturally aspirated diesel engines 20% n/a 50% 40%
Johnson Matthey CEM™ Catalytic Exhaust Muffler and/or DCC™ Catalytic Converter Highway, heavy- duty, non-urban bus, 4-cycle, non-EGR, model year 1998 – 2003 turbocharged or naturally aspirated diesel engines 25% n/a 50% 40%
Johnson Matthey Continuously Regenerating Technology3 (CRT3) Particulate Filter Highway, medium and heavy-heavy duty, 4-cycle, non-EGR, model year 1994 - 2006, turbocharged or naturally aspirated engines 90% n/a 93% 72%
Johnson Matthey Selective Catalytic Reduction Technology (SCRT) On-highway, 4-cycle, EGR and non-EGR, 250-500 hp heavy-duty diesel engines, originally manufactured from model years 1998 through 2006 90% 70% 90% 85%
Johnson Matthey Selective Catalytic Reduction Technology (SCRT) On-highway, 4-cycle, non-EGR, 250-500 hp heavy-duty diesel engines, originally manufactured from model years 1994 through 2002 90% 70% 95% 90%
Konecranes PLC Tier 4F EcoLifting Hybrid System Nonroad, Tier 0, Tier 1, Tier 2 or Tier 3 diesel engine-equipped Rubber tired gantry 90% 90% 90% 90%
Mi-Jack Products, Inc. Tier 4F EcoCrane Hybrid System Nonroad, Tier 0, Tier 1, Tier 2 or Tier 3 nonroad diesel engines on rubber tired gantry cranes 95% 95% 58% 37%
MJ EcoPower Hybrid Systems, Inc. EcoCrane Hybrid System Nonroad, Tier 0, Tier 1 or Tier 2 nonroad diesel engines on rubber tired gantry cranes 74% 84% 96% 71%
Nett Technologies, Inc. BlueMAX™ PLUS 100 Selective Catalytic Reduction (SCR) System Nonroad, 4-cycle engines, rated at 100-750hp, certified to Tiers 1, 2, or 3 85% 85% 60% 95%
Nett Technologies, Inc. BlueMAX™ 100 Urea-Based Selective Catalytic Reduction (SCR) System Nonroad, 4-cycle, non-EGR diesel engines between 75–370 kW power ranges, originally manufactured from 1996 through 2008 and originally certified without a catalyst to EPA Tier 1, 2, or 3 standards 0% 65% 90% 85%
Nett Technologies, Inc. BlueMAX™ 300D Selective Catalytic Reduction (SCR) System 4-cycle, constant speed engines, rated at 100-750hp for NR and Stationary applications, certified to Tier 1, 2, or 3 25% 80% 90% 90%
Nett Technologies, Inc. GreenTRAP NOVA 100 Active Diesel Particulate Filter (DPF) System Non-road, 4-cycle, with or without EGR diesel engines between 175 – 470 hp (130 – 351 kw) ranges 90% 0% 90% 90%
Nett Technologies, Inc. MD300 Diesel Oxidation Catalyst (DOC) 4-cycle, constant speed engines, rated at 100-750hp for NR and Stationary applications, certified to Tier 1, 2, or 3 20% 0% 80% 90%
Various Biodiesel (1-100%) Highway, heavy-duty, 2 & 4-cycle 0 to 47% -10 to 0% 0 to 67% 0 to 47%
Various Cetane Enhancers Highway, heavy-duty, 4-cycle, non-EGR-equipped engines n/a 0 to 5% n/a n/a
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Last updated on March 28, 2025
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