The pro tip: Spark and glow plugs

A combustion engine needs fuel, air and heat. Heat can come from an ignition or preheating source. That’s what spark and glow plugs do. How do they work? When and how to change them? Let’s figure it out together with this new pro tip by Klaxcar.

maintenance plug spark

What is a spark plug?


Spark plugs are found in gasoline engines. By creating a spark, spark plugs generate a combustion. A gasoline engine contains one spark plug per cylinder. A spark plug consists of several parts:

  • a connector to the ignition coil;
  • ceramic insulation;
  • a base composed of a gasket and an electrode.

The spark plug depends directly on the ignition coil. Thanks to the connector, the coil transmits a discharge to the spark plug, which creates the spark.

The different types of spark plugs and ignition coils

There are different types of spark plugs to better fit the gasoline engine. They can differ in terms of:

  • material (platinum, copper or iridium) ;
  • size of the nut or thread ;
  • type of joint (compression or conical washers) ;
  • electrode spacing in the cap.

Similarly, there are different kinds of ignition coils:

  • A conventional coil alone powers the four spark plugs.
  • A ramp coil feeds a couple of candles. It is installed directly on the head of the spark plugs.
  • A twin coil feeds two candles by a wire system.
  • A pencil coil feeds each candle separately.
  • An independent double coil feeds two candles at a time. Each coil is independent, and can be changed on its own, unlike other coil types.

When and how to change an ignition coil ?

When the coil has a sign of wear, the engine can only rely on the cylinders. An ignition coil does not have any specific replacement interval. If it becomes faulty, it can no longer provide the energy needed for combustion. As a result, the car loses power. When all the ignition coils are out of order, the engine no longer starts. If you notice any of these signs, have your vehicle diagnosed to replace the faulty ignition coil in time.

A faulty ignition coil can activate the engine management fault light (orange engine). You can check the status of an ignition coil by plugging an electronic case into the diagnostic outlet. To change an ignition coil, follow these few steps:

  • Disconnect the negative terminal from your battery for safety (risk of electrocution);
  • Unplug the electrical connector;
  • Unscrew the coil(s) to be changed;
  • Screw in the new ignition coil(s);
  • Reconnect the connector and the negative terminal to the battery.

For more safety, we advise you to wear gloves and goggles. As for spark plugs, the replacement interval is between 30,000 and 60,000 kilometers. On the latest gasoline engines, the service life of spark plugs can exceed 100,000 kilometers.


Ignition coils: Klaxcar references and advantages over other brands

Find our selection of ignition coils on the Klaxcar webcatalogue. Compared to other brands, Klaxcar is the professional  choice with the best value for money. We also offer a complete range of spark plugs. In case of doubt, our team is at your disposal to guide you in your choice.


What is a glow plug?

Glow plugs are present in diesel engines whose start-up does not need a spark. By heating, the pressurization of the fuel allows the engine to start. Glow plugs work as electrical resistors that preheat the engine. Once preheated, the engine is in good condition to start. 

While a gasoline-powered car uses spark plugs constantly to drive, the diesel engine no longer needs glow plugs on the road. Glow plugs an important role especially when the vehicle has been stationary for some time or in cold weather.

When and how to change a glow plug?

Glow plugs can show several signs of wear:

  • Difficulty or even impossibility to start;
  • Vehicle blows;
  • An abnormal release of smoke.

The change interval of a glow plug is about 80,000 kilometers. We advise you to replace all your glow plugs at the same time. Otherwise, you could create an imbalance between the different cylinders.  To change the glow plugs, take a torque wrench. Unscrew the old candles and screw the new ones.


Glow plugs: Klaxcar references and advantages over other brands

Discover the Klaxcar range of glow plugs.  Quality at an affordable price: this is what differentiates our webcatalogue from other brands. For more than 25 years, we have been innovating to meet the needs of the car fleet, both in France and abroad!

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