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Diesel Exhaust Fluid (DEF)

The API Diesel Exhaust Fluid Certification Program is a voluntary program designed to certify and monitor the quality characteristics of diesel exhaust fluid intended to operate converters with selective catalytic reduction (SCR) in motor vehicles with diesel engines. Diesel exhaust fluid marketers that meet specific performance requirements for diesel exhaust fluid may be licensed to display the API Diesel Exhaust Fluid Certification Mark.  For more information on this program, including an explanation of program fees, please visit www.apidef.org.  

API maintains a real-time directory of  marketers licensed with the API Diesel Exhaust Fluid Certification Program.  Click here to access the current directory of licensees.

API Diesel Exhaust Fluid Certification has many benefits:  

  • Identifies for consumers diesel exhaust fluids that meet diesel engine manufacturer requirements.
  • Helps consumers find those fluids.
  • Gives consumers a choice of quality brands from which to choose.
  • Helps reduce Nitrogen Oxide emissions.
  • Provides rigorous monitoring of fluids in the marketplace.
  • Tests licensed fluids to ensure that they meet program requirements.

To become licensed, applicants must complete the following steps:

1. Register as a contact at https://dieselexhaust.api.org 
2. Verify email address
3. Enter company information
4. Complete product information for the fluid or fluids to be licensed (brand names, supplier information, and traceability codes for packaged products).  Note that API will not allow licensed brand names that contain any reference to API, ISO, or any terms that infer API endorsement (for example, the terms “certified,” “approved,” “licensed,” “accredited,” “endorsed,” “qualified,” “verified,” etc.).
5. Complete detailed formulation information (physical and chemical properties)
6. Upload supporting test documentation
7. Sign the API License Agreement
8. Generate an application invoice
9. Pay the application fee and enter necessary payment information

The online system will not permit an invoice to be generated until at least one DEF product has been submitted for API review. API reviews applications only after complete payment has been received.

An applicant may not display the API Diesel Exhaust Fluid Certification Mark on any product or refer to the fluid as API certified, licensed or approved until the applicant has paid the application fee, signed the license agreement certifying that the fluid meets API requirements, and received notice from the API online system that the product has been licensed.

To manage an existing license, please click here.   

Also, be sure to update your bookmarks to http://dieselexhaust.api.org.  

Please direct any questions or comments regarding licensing to teamdef@api.org.