Glow Plugs Glow Plugs

Glow Plugs

What are glow plugs?

Glow plugs are specific to diesel engines. Their task is to help start the combustion process of the diesel fuel. Diesel fuel does not ignite with a spark like petrol does but rather it ignites when exposed to heat. When starting a diesel engine the glow plugs heat up until they are red hot. When diesel fuel is injected into the piston chamber it makes contact with the glow plugs which ignites. This starts the combustion process.

How do I choose the correct glow plugs?

Glow plugs are specific to each engine as they need to match the ignition system and the fitment to the engine. The best way to obtain the correct glow plugs for your vehicle is to obtain the original (OE) part number and use that to search for parts that match it.

Obtaining the OE part number is not always possible so here are some factors to consider when selecting replacement glow plugs:

  • Engine code

  • Vehicle manufacture date (this is not the date the vehicle was registered but the date it was made

  • Engine number sequence (up to or after as specific number/letter

  • VIN (chassis number) sequence (up to or after as specific number/letter

  • Please take note of all compatibility information listed with a part that is shown as correct

What brand of glow plugs should I choose?

Glow plugs work in a high heat and pressure environment so better quality parts inevitably will perform better and last longer. Bosch make glow plugs for the original car manufacturers which makes them premium quality. This is also reflected in the price point. There are other brands that offer high quality replacement glow plugs and in some cases may have a longer warranty period than premium brands but at a lower cost. Febi Bilstein, Blue Print, Lucas and NGK have a great reputation so which brand you choose is largely down to your budget and the brand you feel comfortable with.

How can I tell my glow plugs need replacing?

It is not always apparent that there are issues with your glow plugs unless there is a specific warning on the dash of your vehicle. If you are not sure we would always recommend that you have a qualified mechanic diagnose issues with your engine.

Here are some symptoms of a faulty glow plug:

  • Engine struggles to start or will not start

  • Engine misfires

  • The engine has a rough idle

  • Reduced fuel economy

  • Decrease in engine power

  • Excessive exhaust smoke

  • Glow plug error on the dash

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