What is a glow plug?
A glow plug is a heating component used to help diesel engines start up. The glow plug heats the fuel and air to encourage efficient fuel combustion, and the combustion starts the engine so that you can drive.
The glow plug is a pencil shaped piece of metal with a heating device at the end of it. Just as petrol needs spark plugs to start, diesel cars come with glow plugs which function in a similar way.
To indicate problems with this system, a glow plug light will either come on and stay on, flash or blink when a fault is detected by the ECU (engine control - or management - unit). Cars displaying this light should be taken to a specialist glow plug or diesel garage for proper diagnosis and service as soon as possible.
How much does it cost to change glow plugs?
The cost of a glow plug replacement can vary depending on your car make and model. The average cost of replacing glow plugs is £212.85, based on WhoCanFixMyCar data.
Which glow plug replacement service do you need?
Glow plug light diagnostics
If your glow plug light has turned on, you must check this as soon as possible to get to the root cause of the problem. Most of the time, the sooner a problem is diagnosed, the simpler it is to fix. The glow plug light might be due to faulty crank sensors, but there are other issues that can cause the glow plug light to turn on which a mechanic will be able to diagnose for you.
Glow plug replacement
Glow plugs don’t have set times for when they need to be replaced. Instead, you should look at getting glow plugs replaced when they fail to work. As a precautionary measure, it is a good idea to get your glow plugs serviced every year. This is done by removing the glow plug and cleaning the threaded section and the cylinder head lubricated with special ceramic grease.
Broken or seized glow plugs
When it’s time to replace glow plugs, sometimes they are broken or seized up so are not easy to remove. This can happen when the glow plugs are seized from corrosion, rust or carbon build-up.
Top warning signs that your glow plug needs to be checked
Here are the warning signs that your glow plugs may need repairing:
The glow plug warning light comes on on the dashboard.
If your car's engine is hard at starting, it is a common symptom of faulty glow plugs.
Diesel engine misfires can be caused by issues with fuel quality, compression and fuel injection.
Decreased fuel efficiency.
Noticing white smoke when starting your engine up could be a sign of faulty glow plugs
Your engine may produce black smoke from the exhaust pipe, as a result of damaged glow plugs effecting the diesel combustion process.
Is a glow plug replacement necessary?
Yes - If you notice any tell-tale signs that the glow plugs are faulty, it’s definitely time to get your car booked in with a garage technician.
The good news is that glow plugs are extremely long lasting and often run for as long as 100,000 miles. Over time, they deteriorate due to wear and tear, but when they do, they are very cost-effective car parts to have replaced.
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