TextHow to decode spark plugs is a very common problem. This blog will outline how to decode DENSO spark plugs.
DENSO spark plugs follow a specific pattern that can be used for each and every DENSO spark plug. To decipher your DENSO spark plug, you must interpret each character within the part number. Below, a table can be seen that gives each possible character and defines what they mean. ***AN EXAMPLE CAN BE SEEN BELOW THE TABLE***
Table note: asterisks * indicate the number of characters after a specified character that need to be fulfilled in order for the description to be accurate. For example, letter A in special design could be used for part number W22EA. In comparison, letter A*** in special design could only be used for a part number with 3 characters after it such as part number QJ16AR-U, with R-U being the three characters used after ‘A’.
| SOME ROWS MAY NOT BE USED FOR A SPECIFIC PART NUMBER | ||
|---|---|---|
| First Letter (iridium only) | Type of precious metal | F Center: 0.55 mm diameter iridium. Ground electrode: 0.7 mm diameter platinum P Platinum plug S 0.7 mm diameter iridium SV 0.4 mm diameter iridium Z 0.55 mm diameter iridium |
| First Letter | Thread Diameter and Hex Size |
Note: first number, before ‘x’, indicates thread size (in mm) and the second number, after ‘x’, indicates the hex size (in mm) C 12×14.0 P 14×20.6 PQ 14×16.0 K 14×16.0 KJ 14×16.0 PK 14×16.0 SK* 14×16.0 SF 14×20.6 U 10×16.0 XU 12×16.0 W 14×20.6 |
| First number combination | Heat Range | This is a range from hot to cold. The lower the number, the hotter. The range is 9 to 37 with possible combinations including: 9, 14, 16, 20, 21, 24, 25, 27, 29, 31, 32, 34, 37 (37 being the coldest, 9 being the hottest) |
| Letter following first number combination | Thread Reach | A 19.0 mm (Electrode Position: 7 mm) 21.5mm B 19.0 mm (Electrode Position: 9.5 mm) C 19.0 mm (Electrode Position: 5.0 mm) D 19.0 mm (Shroud 2) E (With Gasket) 19.0 mm 20.0 mm E (Tapered Seat) 19.0 mm F 12.7 mm FE 19.0 mm (Half thread) G 19.0 mm (Shroud 2.8) 19.0 mm (Shroud 3.0) H 19.0 mm (Electrode position: 8.5 mm) 26.5 mm L 11.2 mm M 8.6 mm N (Taper seat, Half thread)17.5 mm V (Tapered seat) 25.0 mm None 9.5 mm 11.2 mm 19.0 mm 21.5 mm None (Tapered seat) 8.3 mm 11.2 mm |
| Following Letter | Special Design |
A Double ground electrodes B Triple Ground Electrodes B*** Electrode projection (9.5mm) C*** Electrode projection (5.0mm) D 4-ground electrodes for Mazda R.E. H*** Electrode projection (8.5 mm) K Special type for Honda CVCC LM Special type for Lawnmowers M Compact Type N Racing type (nickel ground electrode) Pt Racing type (nickel ground elctrode) P Projected insulator nose S Regular type T Dual ground electrodes for Toyota T.G.P. X Extra projected insulator nose |
| Following Letter | Internal Construction |
None: non-resister R: resistor |
| Following Letter(s) | Special Gap Configuration |
GL Platinum center electrode L Special type for Honda CVCC and extra project type for moped S Semi-surface gap U U-grooved ground electrode US Star center electrode with U-groove V Thin center electrode Z Thin platinum center electrode with tapered ground electrode C Cut-back ground electrode P Platinum tipped plug for DIS |
| Following Number(s) | Gap |
8 0.8mm / 0.32 in. 9 0.9mm / .035 in. 10 1.0mm / 0.040 in. 11 1.1mm / 0.044 in. 13 1.3mm / 0.050 in. 14 1.4mm / 0.055 in. 15 1.5mm / 0.060 in. 20 2.0mm / 0.080 in. |
Here’s how to decode the Denso part numbers on our most popular spark plug. W16EXR-U11.
W 14mm thread size, 20.6mm hex size. This information was found in the second row in the table.
16 this is an indicator on a range. This means that the part number is more hot rather than cold. This information was found in the third row in the table.
E 19.0mm. This information was found in the third row of the table. This information was found in the fourth row in the table.
X Extra projected insulator nose. This information was found in the fifth row in the table.
R Resistor. This information was found in the sixth row in the table.
-U U-grooved ground electrode. This information found in the seventh row in the table.
11 1.1mm / 0.044in. This information was found in the eighth row in the table.
Second Example: SK20HR11
S: 0.7 mm diameter iridium. This was found by going to the first row of the table and finding the ‘S’ character. Note: because there are two letters before the first number, this means that we must use the ‘S’ in the first row rather than the ‘S’ in the second row.
K: 14×16.0 (ISO Small Hex plug). This was found by going to the second row of the table and finding the ‘K’ character.
20: heat range. This was found by going to the third row of the table and finding the ’20’ combination.
H: Electrode projection (8.5 mm). This was found by going to the fifth row of the table and finding the ‘H’ character.
R: With resistor. This was found by going to the sixth row of the table and finding the ‘R’ character.
11: 1.1 mm gap. This was found by going to the eighth row of the table and finding the ’11’ combination.
We understand that learning how to decode spark plugs can be difficult. If you have any questions for your model, comment the model on this post and we will get back to you as soon as possible.
Give us a call at 616-796-6638 with any questions on how to decode spark plugs!