How to break the NGK code

You have probably already asked yourself what the alpha-numerical combinations on the NGK spark plugs and on the packaging mean.

The combination, consisting of letters and numerals, assigned to each NGK spark plug is not only for type designation, but contains also a logical formula with important detailed information on the function of the spark plug.

NGK applied this spark plug formula to standardise its complete product range and to signify the specific features of the respective spark plug in an unambiguous manner.

This, again, simplifies handling and correct selection of NGK spark plugs, for factory-fitting at the car manufacturers, as well as later on at the dealers, in workshops, and also for the customer.

The typical designation is as follows:

The letter combination (1-4) in front of the heat rating indicates the thread diameter, hex spanner size, and type of design.

The 5th place (numeral is given) indicates the heat rating.

The 6th letter indicates the length of thread

The 7th letter contains information about specific spark plug design characteristics.

The 8th position, a numeral again, is a code for particular spark gaps.

Our advice:

Use NGK assignment list for correct application. Then, you will be surely on the safe side. On request, we will send you our current catalogue free of charge.

If you should have any further questions, beyond this, please contact our product manager Mr. Andreas Götz.