Spark plug electrodes erode over time due to sparking and corrosion. The result is the widening of the gap and a subsequent loss of efficiency.

Replacing worn out spark plugs with new ones reduces misfires and emissions, and restores power and efficiency.

Torque is one of the most important factors of spark plug installation. If under torqued, heat-transfer will be incomplete causing high temperatures. Over torquing can cause damage to the plug and to the engine.

When installing new spark plugs, ALL of them need to be changed. Mixing plugs of various ages will cause the engine to run inefficiently.

Refer to your Owner’s Handbook for further instructions.

1. Use a spark plug socket to suit the hexagonal part of the spark plug to ensure that no burring occurs.
2. When removing the spark plug, ensure that no fouling, such as oil on the outside of the plug, enters inside the engine.
3. When installing spark plugs, clean the seat for the spark plug in the engine, check the gasket, and then mount the plugs on their seats.
4. Place the plugs in vertically and screw in by hand until tight.
5. Then, using a spark plug socket, rotate for between ¼ and ½ of a turn for flat seat plugs (or between 1/5 and1/4 of a turn when they are to be re-used). For taper seat plugs use a 1/16 turn.
6. Tightening too much may cause distortion of the plug housing, and in extreme cases could cause engine damage. Therefore, proper installation of the spark plug is important for life and performance of the spark plug.

*1N· m=0.1020kgf· m

Note: The installation torque values shown above apply to new spark plugs without lubricating the threads. If threads are lubricated, the torque value should be reduced by approx. 1/3 to avoid over-tightening.

This guide is provided for informational purposes only. Always seek the advice of a trained professional before servicing any engine. DENSO is not responsible for the use or misuse of this information and any results thereof. Specifications are subject to change without notice.