DIY How to Change Spark Plugs Yourself Mercedes-Benz

Changing the spark plugs on your Mercedes-Benz is not as difficult as you think. If you have the right tools, we will show you what you need; it is straightforward. This guide provides step-by-step instructions and video clips to help you replace the spark plugs.

While most spark plugs can last over 100,000 miles, it is recommended that you change the spark plugs more frequently than that for optimal performance and better fuel economy.

It will take you a couple of hours to change the spark plugs, maybe even longer if you change them on a Mercedes-Benz for the first time. Ultimately, you will have a smoother-running engine, get better fuel economy, and even get rid of that misfire or check engine light.

You can change the spark plugs on your Mercedes-Benz for under $80 and save hundreds compared to the typical quote of $300 – $500 at most auto repair shops. You don’t need to be a mechanic.

Make:	Mercedes-Benz
Model:	E CLA SLK ML S-CLK CLS GL SL
Years:	1998-2010
Difficulty:	Medium
DIY Cost	$60-$90
Time:	120 minutes
Frequency:	Every 60,000 -100,000 miles

Parts and Tools Needed to Replace the Spark Plugs on your Mercedes-Benz

Here is a list of all the parts that you will need. We have provided links to Amazon for all the parts we use to make it easier for you if you need to purchase any parts.

Spark Plugs

Try to stay with the original equipment if at all possible. If you want your spark plugs to last longer and provide a better spark, we recommend installing iridium-tipped spark plugs instead of platinum. Mercedes-Benz cars have two spark plugs per cylinder, including the E 320. ML 350, S 500, CLK 55 AMG. If you have a six-cylinder engine, multiply that by two, and that’s how many new spark plugs you need.

• 6-cylinder engine, you will need 12.
• 8-cylinder engines require 16.
• 12 cylinder engine, you will need 23.

Did you catch that? For a 12 cylinder engine, you won’t need 23 but 24 spark plugs. Just making sure you are staying awake.

You have several options, such as iridium, platinum, or copper, when it comes to the material of the center core. Iridium spark plugs perform better but also are the most expensive. Copper plugs are the least expensive and will do the job, but they don’t last as long. Below we have provided recommended brands for each type.

Iridium Spark Plugs

Iridium plugs tend to cost a little more, but if you decide to invest in your car, Bosh Iridium Spark Plugs work flawlessly on the Mercedes-Benz Engines. NGK Iridium and Denso Iridium also work great on Mercedes-Benz. While Bosch is the OEM plug for Mercedes-Benz cars, some AMG models are equipped with NGKs.

Platinum Spark Plugs

Most Mercedes-Benz cars since 1995 and after are powered by Bosch Platinium spark plugs. They are cheaper than iridium plugs; you will stay with stock performance.

Cooper Spark Plug

They are the least expensive plugs but also don’t last long. If you want to go this route, you can go for the Bosch F8DC4 copper plugs. These spark plugs have a heavy-duty copper core center electrode for superior reliability. They have an insulator design to help avoid current leakage and misfires. Make sure to gap these spark plugs to 0.044

You could choose either one of these spark plugs. Just remember to order the correct quantity.

Tools Needed

There is one tool that you must have to be able to change the spark plugs in your Mercedes-Benz. That is the Spark Plug Wire Remover Wrench Tool 17mm. You will need this tool to remove the ignition wire boot. We will show you in the video clip how to use this too.

In addition, you will need a

• 3/8 ratchet drive,
• spark plug socket set,
• 3/8″ drive extension set
• magnetic pickup tool.
• torx socket set and a
• torque wrench in ft-lb.
  If you click on any of the links above, you will be redirected to Amazon if you need to purchase any of them.

Step-by-step instructions on how to replace the spark plugs on your Mercedes-Benz

Step 1. Open hood

Prepare the area around your car. Make sure there is no object nearby where you can trip and fall. Next, make sure to work on a cold engine. If the car was running right before, wait for an hour or so for the engine to cool down, or you can burn your hands. Use a pair of gloves to protect your hands.

Step 2. Disconnect the battery

We recommend that you disconnect the battery before you start work. The battery is located in one of these three places:  the engine bay, under the rear seat, or the trunk. Disconnect the negative battery cable only; no need to disconnect both terminals.

Step 3. Remove engine cover

You may be intimated by the engine cover that doesn’t allow you to see anything on the engine or where the spark plugs are but don’t be. The engine cover can be easily lifted. It is not held in place with any bolts or screws. Four clips hold it in place, so go ahead and pull it up. The cover may look slightly different on your car, but the principle is the same.

Step 5 Location of spark plugs and coils

Next, locate the spark plugs and coils. We will need to remove the coils to make it easy to access the spark plugs. Don’t worry; it is easy. Here is a picture that shows all the spark plug coil locations.

Step 6 Unplug ignition coil packs.

Disconnect the electrical connector from the spark plug ignition coil. Press the plastic tab and pull the connector away from the ignition coil. The plastic connectors can break easily, so be careful. If any of them, don’t panic; you can use zip ties around the connector when you install them.

Step 7 Remove the ignition coil.

Removing the spark plug boots will be easier if you can move the ignition coils out of the way. Remove the bolt at the center of the ignition coil pack using a torx socket wrench.

Step 8 Remove the ignition wire.

Use the 17 mm special tool to remove the ignition coil wire. Note that the top ignition coil wire goes to the forward plug marked with an A, and the bottom ignition coil wire goes to the rear spark plug marked with a B.

Here is a clip that summarizes all these steps.

 

Step 9 Remove old plugs.

Use the socket, extension, and ratchet to remove the old plugs. It will be challenging to see the spark plugs as there isn’t enough room for you to look at them. The picture below is worth gold and is the best picture of the spark plugs and where they are installed.

Removing all the 12, 16, or 24 spark plugs will take a while, depending on your application. Removing and installing new plugs one at a time is a good idea. Don’t drop anything inside the engine via the spark plug hole. You may want to use some anti-seize lubricant to put on the threads when you install the new plugs. If you have a magnetic pickup tool, keep it around because you will need it.

Step 10 Install new spark plugs.

Install new spark plugs one at a time. If you are installing copper spark plugs, make sure to gap them to 0.044 using aspark plug gauge.

Step 11 Torque spark plugs to 18 lb-lbs

Use a torque wrench such as the Tekton 3/8 torque wrench to tighten the spark plugs to 18 ft-lb (~25 Nm) for engines 113.987/988/990/991. Most other engines require 21 ft-lb (~28 Nm) of torque. This is very significant, especially for the aluminum alloy head. You should avoid over-tightening the new plugs to prevent damage to the threads. Also, you don’t want to leave the spark plugs loose, as it is essential that they don’t allow any leakage during compression or, even worse, pop out and damage your car.

Helpful Tips

A helpful hint would be to remove the rubber plug insert in the spark plug socket when installing the new spark plugs, especially for the driver’s side since it’s a little tighter on that side.  That way, the socket won’t become detached from the extension when removing the socket after installation. Suggestion by Bill A.

What are the best spark plugs for Mercedes-Benz? 

We would recommend that you install the original equipment spark plug. If you do want to upgrade, a good choice would be BOSCH Iridium Spark Plug for Mercedes-Benz.

What is the Best Scanner to use to Diagnose Spark Plugs Problem?

The YOUCANIC full system diagnostic scanner is a valuable tool for Mercedes-Benz owners who want to troubleshoot problems with their vehicles. This advanced scanner can read and interpret fault codes from the car’s computer system, providing detailed information about engine, transmission, brakes, or other critical system issues. The scanner can also perform diagnostic tests on various systems, including the ABS, airbag, and steering systems, to help pinpoint the root cause of any issues. With this information, you can make more informed decisions about repairs and maintenance, saving time and money on costly repairs.

In addition to its diagnostic capabilities, the YOUCANIC scanner can help you reset maintenance reminders and service indicators, allowing you to stay on top of your vehicle’s regular maintenance schedule. This is important because regular maintenance is essential for keeping your Mercedes-Benz running smoothly and preventing significant problems down the line. Using the YOUCANIC scanner, you can ensure that your vehicle is always in top condition, reducing the risk of breakdowns and other issues that could cause inconvenience or costly repairs. Whether you’re a DIY mechanic or a professional technician, the YOUCANIC full system diagnostic scanner is essential for troubleshooting Mercedes-Benz problems and keeping your vehicle in top condition.