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Glow plug relay

The glow plug relay controls the preheating of the glow plugs in a diesel car. Diesel ignites under high pressure when it comes into contact with oxygen. This does not require a spark, like a petrol engine does. However, the fuel must be gaseous for this, and this is where the glow plug comes in. By heating up the fuel, the car can start reliably, even on a cold day. The glow plug is heated by the glow plug relay. In early diesel engines, this preheating could take a long time, nowadays, it only takes a few seconds.

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The glow plug relay is the component that supplies power to the glow plug. A relay is a type of switch that works on the basis of magnetism. When the relay is energized, the electromagnet attracts a small sheet of steel. This completes a circuit, which allows the current to be passed to the glow plug and heat it up. When the engine is warm, the relay is turned off and the circuit is broken. Many electrical components in the car are controlled by this type of plug-in relay.

Glow plug relay broken 

When the glow plug relay is not working properly, the fuel is not heated up before it's compressed in the cylinders. This causes the fuel to have trouble igniting. This can be noticed from a fluctuating speed or so-called "diesel engine knock", these are vibrations when accelerating while the engine is still cold. 

You can easily find a new glow relay for your car at Winparts. With our large selection, we offer glow plug relays for a variety of car brands and models. You find suitable parts by entering your licence plate number and with our fast delivery times, you will soon be on your way again. Do you still have questions? Our expert customer service team is ready to help you with every step of your order.