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D. C. Johnson

D. C. Johnson is best known for the ubiquitous "Johnson Box".  Designed to retrofit European Automobiles manufactured for sale and use in Europe and other regions, to meet emissions regulations requirements for sale and use in the United States of America. 

A brief history

In 1981, Dave Johnson was asked to design an Air/Fuel control unit similar to the OEM units for European cars. The OEM parts did not always fit the European spec. cars, and many European specification cars sold for use in Europe were finding their way to the US.  By mid 1982 D. C. Johnson was producing two models of these Air/Fuel control units, and in 1983 began selling complete emissions control conversion kits and conducting training classes for the installation and compliance process.  This market continued to grow for the next several years, until emissions regulations in Europe became similar to those in the US.

D. C. Johnson today

  • Many of the original D. C. Johnson Air/Fuel control units remain in reliable service after over 30 years.
  • For owners of genuine D. C. Johnson emissions control products, we provide technical information to assist in maintenance, installation rework, calibration and repair of the original genuine D.C. Johnson and Associates Inc. emissions control products.

Contact Information

          Inquiries please email us at info@dc-johnson.com.

Product Spotlight

Product Spotlight FAC-1

The FAC-1 Air/Fuel Ratio Controller


The PCBA (Printed Circuit Board Assembly) of the original FAC-1 Air/Fuel ratio controller for CIS (K Jetronic) fuel injection equipped Automobiles.

First conceived in 1981, The unit pictured above is a revision D example produced in 1984.