Installation and Operation of the Caterpillar Diesel Particulate Filter (DPF) and the Diagnostic Module for Non-Road Machine Applications (Non-California Applications)

Caterpillar Products: All (Except Unregulated, Tier 0, Tier 3, and Tier 4 Engines)





Diesel Particulate Filters (DPF) are not applicable to all engines. Diesel Particulate Filters intended for usage on diesel fueled engines only. This technology does not apply to engines that use any other fuel other than ultra low sulfur diesel fuel. A DPF should not be applied to any engine that does not meet all the requirements set forth in this document. The performance conditions required for installation and operation of this technology can be found on the EPA Verified Technologies List web site. Be sure to see all letters and attachments.

All installations must include the Diagnostic Module. The Diagnostic Module monitors temperature and pressure conditions providing critical information to the operator. If the required temperature profile is not met, the DPF will not function properly resulting in possible Engine/DPF damage or failure. Upon initial installation of any DPF, a backpressure reading must be taken and recorded for future comparison.

The DPF replaces the muffler and may require additional heavy-duty brackets and other modifications/fabrications for proper installation. Consult your Caterpillar Dealer Technical Communicator for specific installation questions.

The Caterpillar Diesel Particulate Filter System includes (see Illustration 1) the following: a diesel oxidation catalyst, a particulate filter, exhaust temperature/pressure monitor ( 423-5875 Clean Emissions Module or the 423-5876 Exhaust Monitor Gp which includes the Diagnostic Module (see “”Parts List” ” section), thermocouple and parts needed for installation.

Note: Caterpillar requires that every vehicle equipped with a Diesel Particulate Filter must install the 423-5875 Clean Emissions Module for warranty and maintenance purposes.

Typical DPF Unit (Diagnostic Module not shown)

Diesel Particulate Filter Operation

The Caterpillar Diesel Particulate Filter (DPF) is used to reduce greater than 85% of the emissions of particulate matter (soot). These emissions are reduced by filtration as the exhaust passes through the DPF wall. Carbon monoxide (CO), and Hydrocarbons (HC) are also reduced as the engine exhaust passes through the catalytic oxidation and filtration units. The DPF filter substrate uses a series of alternately blocked channels which forces exhaust gasses to flow through the channel walls. Particulates are physically captured and chemical reactions take place (see Illustration 2). Carbon monoxide and hydrocarbons are converted into carbon dioxide and water vapor. These filters are self-regenerating. Self-regenerating filters are not disposable, but, instead, will “burn off” the accumulated soot continuously if the proper exhaust temperature profile is met.

DPF Wall Flow Design

Proper DPF regeneration REQUIRES the following conditions:


  • Ultra Low Sulfur Diesel Fuel Must Be Used. Ultra Low Sulfur Diesel Fuel must have an average sulfur content of 15 parts per million (ppm).
  • Ultra Low Sulfur Diesel (ULSD) fuel (≤ 15 ppm (mg/kg) sulfur) is required by regulation for diesel engine use in California. The United States (U.S.) Environmental Protection Agency (EPA) defines Ultra Low Sulfur Diesel (ULSD – S15) as a U.S. diesel fuel with a sulfur content not to exceed 15 parts per million (ppm (mg/kg)). Also, the sulfur content in the diesel fuel is not to exceed 0.0015 percent by weight. ULSD fuel must meet the S-15 fuels designation in the latest edition of ASTM D975 and/or conform to Caterpillar Fuel Specification.
  • Failures that result from the use of improper fuels are not Caterpillar factory defects. The use of Low Sulfur diesel (500 ppm or mg/kg) or any other diesel fuel than Ultra Low Sulfur diesel fuel is illegal. The warranty may also be affected.
  • Biodiesel fuel may be used up to the B20 blend level (20% biodiesel and 80% appropriate ULSD fuel) IF the final B20 blend conforms to ASTM D7467 and API gravity 30-45. The neat biodiesel blend stock should conform to ASTM 6751.
  • The engine exhaust temperature at the DPF inlet must be 240° C (464° F) or greater for at least 40 percent of the time.
  • The ratio of nitrogen oxides (NOx) to particulate matter (PM) must be a minimum of 25:1. This ratio is the NOx level, in grams/brake horsepower hour, divided by the PM level). This technology is currently applicable to 1996 or newer Tier I or Tier 2 engines. Current Caterpillar retrofit passive DPF product is not applicable to Tier 3 engines.
  • Consult with State and Federal agencies for verification requirements.
  • The engine should be maintained and must not consume oil at a rate greater than the rate specified by the engine manufacturer.
  • Caterpillar DEO-ULS (Ultra Low Sulfur) 319-2260 Oil exceeds the performance requirements of API category CJ-4 oil and is recommended due to a low ash specification. Engine oil that meets or exceeds the specifications in the Caterpillar ECF-3 or API CJ4 Categories may be used in these applications. Oil burned during the combustion process accounts for almost all of the DPF ash accumulation (because of oil additives). The use of the recommended low ash oil results in lower ash accumulation in the filter. Failure to use the recommended grade of oil may result in more frequent ash removal service intervals.

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