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Mercedes Benz Ignition Coil Problems – Symptoms, Diagnosis and More

Mercedes Benz Ignition Coil Problems - Symptoms, Diagnosis and More

Ignition is all about precise timing, efficiency, and consistency. It’s arguably the most important system when it comes to internal combustion engines. Running into issues with your ignition can be difficult to diagnose, especially on cars that run systems we can only describe as ‘different’ compared to most others. Mercedes Benz ignition coil problem covers such complex systems thanks to their dual ignition coil design and the famous twin spark technology. Let’s dig in.

What is an Ignition Coil, and How Does It Work?

Before we get into the specifics of ignition coil failure, it pays to know what an ignition coil is and how it works. We won’t go too deep into ignition coils, though. If you want to know more, check out our guide on modern ignition coils.
Modern gasoline engines require a source of ignition to combust the fuel inside the cylinder. Providing that source of ignition isn’t easy when the most your car’s electrical system has to offer is measly 12 Volts of power.
An ignition coil’s job is to take those 12 Volts and turn them into high voltage power necessary to ignite the fuel. In a way, an ignition coil is a voltage booster. The way it works is rather ingenious. You have two coils of wire wound around a solid laminated core. One coil is light with only a few turns of wire while the other one packs thousands.
Once supplied with power, the primary coil is energized and creates a magnetic field which builds up the voltage. When the right amount of voltage is reached, the stored energy is discharged through the secondary coil and into the spark plug. The resulting surge of power is enough to make the spark, ultimately igniting the fuel.

Mercedes-Benz Ignition Coil - Bosch 00107 eEuroparts.com
Four Bosch 00107 ignition coils are in view on this V8 out of an SLK55

Mercedes Benz Ignition Problems – Understanding Different Types of Ignition Systems

Mercedes Benz is often considered as one of the more innovative brands in the automotive industry. They were the first to run 4 valves per cylinder. They also came up with a supercharger, ABS, the airbag, you name it. MB’s knack for innovation led them to investigate advanced means of fuel ignition as well. As a result, you’ll find Mercedes Benz vehicles with the standard single-coil<b/ single spark (per cylinder) systems as well as those with a twin spark system.
We’ll jump into single-coil pack problems later on. First, we’d like to take you into the remarkable world of twin spark ignition systems for a moment!

Twin Spark Ignition

If you’re a car enthusiast, the chances are that you’ve heard of Twin Spark technology. Developed by Alfa Romeo back in 1914, this innovative ignition system promised improvements in terms of power and flexibility.
Alfa Romeo revamped this tech back in the early ’90s with their 1.6TS, 1.8TS, and 2.0TS engines. Although they were the first, Alfa Romeo wasn’t the only car manufacturers to jump on this idea. Mercedes Benz had also explored the world dual ignition systems. Here’s how it works.

What is an Ignition Coil, and How Does It Work?
You can see the two separate coils housed in the assembly from this angle

The Idea behind Twin Spark Ignition Systems

Igniting the fuel/air mixture inside a cylinder isn’t as simple as providing the spark. The position of the spark, as well as its timing, both play a significant role in the efficiency of combustion. Many car manufacturers have tried to boost their engines’ effectiveness by playing with timing, fuel/air mixture, and other relevant parameters. Alfa Romeo engineers did something completely different.
Instead of trying to squeeze more power out of the existing design, they simply added one more spark plug per cylinder. With two spark plugs offering near-simultaneous spark, they’ve managed to significantly improve the efficiency of combustion, thus gaining a more complete burn and more power. Furthermore, improved efficiency of combustion means better fuel efficiency.

Mercedes Benz Dual Ignition Coils

Much like Alfa Romeo, Mercedes Benz has also looked into adding an additional spark plug per cylinder. Granted, they’ve used this technology mostly in their high-power V6 and V8 engines built from 2000 up until 2006. Mercedes Benz was done using this technology in 2009 with the SLK 55 AMG and its impressive 5.5-liter V8.
Unlike Alfa Romeo, Mercedes had turned to twin spark tech out of necessity. High displacement engines meant large cylinder bores, sometimes up to 700cc per cylinder. Igniting the fuel in a large cylinder efficiently had was an issue. Adding an additional spark plug was a logical solution.
The additional spark plug meant a more complex ignition coil design. Mercedes Benz had used the Bosch 00107 across a wide range of these engines. That being said, Karlyn part number 5046 is considered to be a good alternative, especially because it packs two separate coils within one housing.

Dual Spark Plug Terminals Bosch 00107 mercedes benz ignition coil problem
Dual Spark Plug Terminals

Ignition Coil Issues – Recognizing the Symptoms

Recognizing ignition coil issues can be difficult, but it doesn’t have to be. It all comes down to whether the issue is constant or if it’s an intermittent event. One good thing about Mercedes Benz‘s dual ignition coils is that they’re fairly affordable. We can thank the fact that they used this type of coil in so many engines, which dramatically reduced the unit’s price.
As far as the actual symptoms go, they are more or less in line with general ignition coil symptoms for most cars. Here are some of the common problems you might experience if your coils are on their way out.

Misfire on One or More Cylinders

Misfire is a common problem with gas engines. A lack of spark usually causes a misfire, lack of compression, or lack of fuel in that specific cylinder—the very first step when diagnosing any misfire issues to find out which cylinder is affected.
This can be tricky if you don’t have an OBD II reader, or if your reader isn’t giving you a specific P0300 cylinder misfire code (it would be P0301 for cylinder one, P0302 for cylinder two, etc.). If you have an OBD II reader and you’re getting P0300 errors and nothing else, the chances are decent that it’s an ignition coil or a spark plug issue.

Signs of Engine Misfire

Although and OBD II reader is a surefire way of diagnosing engine misfire problems, other symptoms can point to this issue.

  • Loss of power – You’ll feel that your car isn’t pulling like it used to. The lack of power can be intermittent as well.
  • Vibrations – A misfiring engine is generally going to cause rough idle as well as vibration at lower RPMs. That being said, vibrations caused by cylinder misfire tend to disappear when you go over 2,000-3,000 RPM.
  • Poor Performance – Overall poor performance is definitely a potential issue when dealing with an engine misfire.
  • Check Engine Light – Any of the symptoms mentioned above paired with a check engine light signifies something wrong with the car. Don’t ignore the check engine light longer than you absolutely have to.

Why do Ignition Coils Fail?

The reasons for ignition coil failure on Mercedes Benz engines are numerous. Ignition coil windings can get damaged over time due to vibrations. Something could also damage an ignition coil’s insulation, causing a short or exposing the coil to external influences.
That being said, one of the leading sources of ignition coil failure is a bad spark plug. Spark plugs need to be changed per manufacturer’s instructions. A bad spark plug can lead to voltage issues that eventually overpower the coil, causing it to fail. As a result, you’ll often find a bad spark plug under a bad coil.

How to Prevent Ignition Coils from Failing?

It isn’t much you can do about this, aside from proper maintenance. Make sure to change your spark plugs as necessary and only use quality brands. This alone is enough to prevent a good portion of issues with the ignition system.
If you don’t change your plugs when necessary, you’re risking them, developing a more massive gap. That means the ignition system has to work harder to create a spark that will bridge the increased gap, which strains the coils.
Engine maintenance is also key as ignition coils aren’t an isolated system. There are cases of engine oil creeping up the spark plug and causing shorts within the ignition system.

Finding the Right Ignition Coil for Your Mercedes Benz

We at eEuroparts.com understand that maintaining a Mercedes Benz is all about choosing the right parts. That’s why we’ve built one of the largest catalogs of Genuine and OEM parts for Mercedes Benz vehicles in the United States. To find the right ignition coil for your car, simply head over to our store and input your vehicle’s year, make and model into our navigation tool.
You can use the VIN of your car to find the exact matching parts for your specific vehicle. If you have any questions regarding our product range, feel free to get in touch with us. You can reach us via email or by giving us a call. Our customer service is standing by to offer assistance!

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