The main function of the glow plug in diesel engines is to provide additional energy to start the engine. When the weather gets cold, glow plugs are vital. Diesel engines rely on the heat of compression rather than spark plugs to ignite fuel in the cylinder. But in low temperatures, the cold engine block absorbs any compression heat which makes starting difficult.
The orange glow plug light on the dash will shine for longer before extinguishing if your glow plugs are wearing out and the car might struggle to start. In cold weather it may feel like you have a flat battery as you will crank the engine trying to start it but this will drain the battery of its charge.
As most cars have four-cylinder engines, you have four glow plugs. If one glow plug fails, the engine may still start but it might run roughly initially. That’s because it will take a bit of time for the cylinder without the functioning glow plug to get up to temperature and work properly. If that’s happening it’s telling you that the glow plugs need replacing.
We have a good range of glow plugs for most car makes and models.