The Mercedes diesel engine is world-renowned for its reliability in all sorts of weather. Part of this reliability stems from the glow plug, a standard component in all diesel autos. The glow plugs are controlled by a glow plug timer relay. Without this particular part working correctly, your diesel engine will not operate, especially during cold weather. Follow along to learn more on the important function of your glow plugs and what happens when a Mercedes glow plug timer relay fails.

Purpose of Glow Plugs

Before understanding what happens when you have a faulty glow plug timer relay in your Mercedes, we need to understand the concept of the glow plugs themselves. You’ve probably heard of spark plugs on a gas engine. For diesel engines, spark plugs do not offer enough ignition power to combust the fuel. Diesel engines count on high temperatures to ignite the diesel fuel and oxygen mix going into the cylinders.

Glow plugs heat the cylinders to a point where combustion begins to take place. Once the process starts and the engine is at a critical temperature, the glow plug timer shuts off the glow plug when no longer needed.

Signs Your Glow Plug Timer Relay Has Failed

Common issues with a glow plug timer relay affect the glow plugs themselves. Here are a few common signs that you need to have your Mercedes checked for problems with the glow plugs.

  • Engine Starting Problems: Without the right temperature to allow for combustion, your Mercedes diesel engine will not start. If the glow plug timer relay is malfunctioning, it may not allow your glow plugs to function at all.
  • Poor Engine Performance: If the glow plug timer shuts down the glow plugs before your engine reaches the vital temperature to combust efficiently, your engine will perform poorly. Stalling and misfires will occur as not all of the fuel and oxygen mix ignites. This can cause damage to your environmental system, as unburnt fuel will enter the exhaust.
  • Check Engine Light: Thankfully, your Mercedes is equipped with warning indicators when systems do not function properly. When your glow plug system components do not work properly, you will receive either a glow plug warning light or a check engine light. After a warning indicator has illuminated, do not continue to operate your Mercedes until you have the opportunity to have it checked out by an expert.

As mentioned, damage can occur to your environmental system and other diesel engine components. Your Mercedes control computer is designed to adjust to poor fuel and oxygen mix. This means your vehicle will probably run, although poorly. However, continuing to operate the vehicle with a bad glow plug relay timer will cost you in major repairs later.

What to Do When Your Glow Plug Timer Relay Fails

If any of the signs begin to show themselves of a failed glow plug timer relay or a failed glow plug problem, take your vehicle to a qualified Mercedes repair shop to run a complete diagnostics test. Don’t trust your Mercedes to just anyone. Only dealer alternative repair shops with experience, certification, and training to properly service your Mercedes are qualified.

A qualified shop will have the state of the art equipment to troubleshoot your glow plug and other issues and have certified technicians who understand how to use the equipment. Even before a repair is needed, a qualified Mercedes service can find your diesel engine issues before turning into an expensive repair. Setting up and keeping to a scheduled service plan will ensure your glow plugs and other essential components function as designed on your Mercedes diesel.

The Benz Shop: Your Trusted Mercedes Service Center

Many choose not to pay dealership prices only Mercedes Glow Plugs to wait on their car’s repair for several days. If you find yourself in need of diagnosing a glow plug or timer relay issue, bring your Mercedes to us at The Benz Shop serving Scottsdale, Glendale, Tempe, Chandler, Paradise Valley, and Phoenix, AZ.

Our trusted and ASE certified technicians have years of experience servicing high-end imports like the Mercedes. Call us today to have your Mercedes diesel set up on a service plan that will save you money on costly repairs later.

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