How you crack the NGK code

The combination of letters and numbers assigned for every NGK spark plug is not only the type designation, it is a logical formula which contains the important details for the function of the spark plug.

You have probably wondered what the letter-number combinations on the NGK spark plugs and their packages mean.

The combination of letters and numbers assigned for every NGK spark plug is not only the type designation, it is a logical formula which contains the important details for the function of the spark plug.

With this spark plug formula NGK has standardised its entire assortment and made the specific characteristics of the respective spark plug clearly recognisable.

This in turn simplifies handling and making the right selection of NGK spark plugs, both in original equipment at the automobile manufacturers and later with the dealers, in the workshops and ultimately for the customer.

The typical designation is as follows:

  • The letter combination (1-4) before the heat rating indicates the thread diameter, hexagon spanner width and the design.
  • The 5th position (number) stands for the heat rating.
  • The 6th letter identifies the thread length.
  • The 7th letter contains data about special spark plug construction features.
  • The 8th position, another number, codifies special electrode distances.

How you crack the NGK code

The combination of letters and numbers assigned for every NGK spark plug is not only the type designation, it is a logical formula which contains the important details for the function of the spark plug. (PDF, 73 KB)

Our tip:

Use the NGK allocation list for the correct application, then there will be no doubt. Take a look in our current catalogue, which you will find in the download area.