An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Verified Technologies for SmartWay and Clean Diesel

Caterpillar Technology—Converter GP- Catalytic Technology (CGP) System

This retrofit technology is included on EPA's Verified Technologies List for Clean Diesel.

On this page:

Technology specifications

Engine Model/Application

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.

Retrofit Fuel, Max Sulfur 15 parts per million (ppm)
Reduction in particulate matter (PM) 95%
Reduction in nitrogen oxide (NOx) 15%
Reduction in hydrocarbons (HC) 95%
Reduction in carbon monoxide (CO) 95%

Top of Page

Criteria to achieve emission reductions

The following criteria must be met in order for appropriately retrofitted engines to achieve the aforementioned emission reductions:

  1. The Caterpillar CGP system is appropriately installed on excavators with engines as described above, and operates with an exhaust temperature at or above 240 °C for 40% of the machine’s duty cycle and not to exceed 600 °C.  
  2. The vehicle must be operated on ultra-low sulfur diesel fuel (ULSD) of 15 ppm or less.
  3. The vehicle must always have a supply of Diesel Exhaust Fluid (DEF) that meets and displays certification of the American Petroleum Institute ISO Standard 22241-1 quality requirements that ensures the proper purity and concentration of 32.5% of urea. The vehicle must be designed to track and log, in nonvolatile computer memory, all incidents of engine operation with inadequate DEF injection or DEF quality.
  4. The CGP system shall not be sold or operated in geographic areas where the DEF may freeze (-20°C), unless it is equipped with tank heaters and DEF line heaters to prevent freezing. It also shall not be operated in areas with temperature above 52 °C and operating height over 3,000-meter. 
  5. Caterpillar is required to provide the operator with clear and visible instructions for maintaining DEF for proper system operation.
  6. Each installation will be equipped with a monitoring system that displays warning lights visible to the operator and audible alarms for low DEF tank level, high CGP inlet temperature and system abnormalities. The monitoring system will also store diagnostic error codes related to DEF tank level and system malfunctions.
  7. Caterpillar is responsible for informing customers, in writing, that disposal of the CGP SCR system must be handled in accordance to all applicable federal, state, and/or local laws.

Top of Page

Verification Letters from EPA

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.