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Mercedes Glow Plug Warning Light

How Glow Plug Timer Relay Failure Affects Your Mercedes In Pineville

by Dutch Silverstein June 8, 2021

Unlike regular gasoline cars, Mercedes diesel engine cars use something called a glow plug, the diesel engine’s alternative to a spark plug. This provides the necessary heat to the engine so that it can start properly when you turn the engine on.

To help them know when and for how long to stay on, glow plugs rely on the glow plug timer relay. If either of these two pieces malfunctions, it could lead to serious performance and ignition problems.

But don’t worry! If you don’t know anything about glow plugs or their timer relays, this article is for you. We’ll be going over what these components do and what signs to watch for that indicate there’s a problem.

The Function of Glow Plugs and Glow Plug Timer Relays

Diesel engines and gasoline engines operate in different ways. One of the biggest differences is that they don’t rely on a spark to start the combustion process. Instead, they use intense heat and pressure to start the engine. A glow plug’s job is to warm up the engine cylinders which allows them to properly combust.

However, a glow plug can’t be on all the time, because that would reduce efficiency and cause damage to the engine. Similarly, a glow plug that’s off at the wrong times can also cause problems. That’s where the glow plug timer relay comes in. Its job is to tell the glow plugs when to turn on and off and how long they should stay in that state.

When the timer relay fails, glow plugs will have no idea of when they’re needed and may activate or deactivate at inopportune times, or just stay on or off indefinitely. This can lead to significant performance issues which can range from annoying to dangerous.

Signs of Glow Plug or Timer Relay Failure

It’s easy for an expert Mercedes technician to diagnose the problem and fix it with the right diagnostic tools & equipment. To help speed up the process even more, you’ll want to be able to tell your mechanic what symptoms you’re experiencing. Here are some of the most common indications of failure in these areas:

  • Check Engine Light or Glow Plug Warning Light Comes On: Modern cars are essentially giant computers, and when something goes wrong inside them, the engine control unit (ECU) will let you know by turning on warning lights on your dashboard. An experienced Mercedes mechanic has specialized equipment that allows them to read the error codes attached to the warning light and figure out the problem quickly from there.
  • Problems Starting Your Car: Because glow plugs are so essential for getting the combustion process started, a malfunctioning glow plug or timer relay often means that your Mercedes will have difficulty starting or that you will be unable to start the car at all. This is because the timer relay isn’t properly communicating to the glow plugs about when to activate.
  • Performance Issues/Engine Misfires: When the glow plug timer relay isn’t working, the glow plugs won’t know when they’re needed. This can lead to misfires as the glow plugs turn on or off at the wrong times. Even if there are no misfires, you may notice a general decrease in the efficiency of your engine.

How to Get Help for Your Mercedes

Because Mercedes vehicles are so unique, they require specialized equipment and tools to properly service them. That’s why it’s best to take your car to see a professional when you’re having trouble with your glow plugs or any other issue. They’ll be able to provide you with prompt, high-quality repairs, so you can rest easy knowing your car is in good hands.

Mercedes Glow Plugs

A&M Auto Service is located in Pineville, North Carolina. We provide services to the surrounding cities such as Charlotte and Greensboro, and we are happy to help you get your Mercedes back into working order. We’ve been in the auto repair business for over 23 years, and our expert mechanics specialize in European import brands such as Mercedes.

If you’d like to learn more about what we can do for you, feel free to contact us today. Our friendly staff is happy to meet you and have a conversation about your Mercedes needs and maintenance.

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