Manufacturer's Numbering Systems

Wondering what the numbers and letters on a spark plug mean? These spark plug charts explain how each manufacturer's numbering system works.

AC Delco Numbering System

 

Autolite Spark Plug Numbering System

 

Bosch Spark Plug Numbering System

 

Champion Spark Plug Numbering System

 

Denso Spark Plug Numbering System

 

NGK Spark Plug Numbering System

NGK Resistor Cover Numbering System