NGK Sparkplug coding explained

NGK Spark Plug Codes:

NGK code: [B] [P] [6] [E] [S]

**Field two: Construction**
C	Hex size 5/8″
K	Hex size 5/8″ with projected tip (ISO)
M	Compact type
P	Projected insulator type
R	Resistor
SD	Surface discharge for rotary engines
U	semi-surface discharge
Z	inductive suppressor

**Field three: Heat Range**
2	Hot
10	Cold

**Field four: Thread reach**
E	19 mm
F	tapered seat
H	12.7 mm (1.5″)
L	11.2 mm (7/16″)
	If this field is blank, an 18 mm diameter plug has 12 mm reach; and a 14 mm plug has 9.5 mm (3/8″) reach.

**Field five: Firing and construction**
A,B	Special design (no details given)
C	special ground electrode
G	Racing use
GV	Racing V-type
H	Half thread
K	2 ground electrodes
L	Half heat range
LM	Compact lawn mower type
M	2 ground electrode for Mazda rotary engine
N	Special ground electrode
P	Platinum tip (premium)
Q	4 ground electrodes
R	Delta ground electrode for BMW
S	Standard 2.6 mm electrode
T	3 ground electrodes
V	Fine-wire electrode, gold-palladium
VX	Platinum tip (high performance)
W	Tungsten electrode
X	Booster gap
Y<	V-groove centre electrode