FAQs
Basic Information
A spark plug delivers electric current from the ignition system to the combustion chamber, creating the spark that ignites the compressed air-fuel mixture.
NGK spark plugs are engineered for consistent ignition, heat resistance, and long service life across a wide range of vehicle applications.
The heat rating indicates how quickly a spark plug transfers heat away from its firing tip. Choosing the correct rating helps prevent fouling, pre-ignition, and overheating.
NGK part numbers identify important specifications such as thread size, reach, heat range, resistor type, electrode design, and special features.
Use the vehicle manufacturer recommendation or a reliable part finder, then confirm the plug type, heat range, thread reach, and gap before installation.
The firing end can show signs of normal operation, carbon fouling, overheating, oil contamination, or incorrect heat range, making it useful for engine diagnosis.
The corrugations increase the surface distance between the terminal and metal shell, helping prevent electrical leakage and flashover.
Information on Various Types of Spark Plugs
A resistor spark plug includes internal resistance that helps reduce electrical noise which may interfere with radios, ECUs, sensors, and other electronics.
A V-grooved spark plug has a center electrode groove that helps the spark form near the outer edges, improving ignitability in many operating conditions.
Iridium IX spark plugs use a fine iridium center electrode for strong ignitability, stable performance, and improved durability compared with standard nickel plugs.
A racing spark plug is designed for high-compression, high-temperature, and high-rpm engines where stronger heat resistance and ignition stability are required.
Projected-tip, V-groove, and other designs that improve firing-end temperature and spark exposure can help reduce carbon fouling when matched correctly to the engine.
Special-type spark plugs may use unique electrode shapes, precious metals, extended reach, compact dimensions, or other features for specific engines and operating demands.
Practical Information
Fouling happens when carbon, fuel, or oil deposits build up on the firing end and weaken or block the spark.
Overheating can cause electrode wear, insulator damage, pre-ignition, rough running, and possible engine damage if the issue is not corrected.
Good ignitability means the spark plug can reliably ignite the air-fuel mixture across starting, idling, acceleration, and high-load driving conditions.
A brownish stain in that area is often corona stain from electrical discharge and does not necessarily mean combustion gas is leaking.
Yes. Spark plugs should be tightened to the recommended torque for the plug and engine type to avoid poor sealing, thread damage, or shell distortion.
Confirm the plug type, reach, seat style, terminal type, and gap. Install into clean threads and avoid over-tightening or cross-threading.
Service life depends on the plug material, engine condition, fuel quality, and driving habits. Follow the vehicle maintenance schedule for replacement intervals.