Today we’ll be changing the spark plugs on a W203 C200 Mercedes-Benz C-Class. Changing spark plugs in this vehicle is a very simple process, if not easier than an oil change.

Difficulty Rating


Tools/Parts Required

  • Socket Set
  • E8 Torx Socket
  • Spark Plug Socket
  • Torque Wrench
  • x4 Replacement spark plugs (We used Denso IKH20TT)
  • Aluminium grade anti-seize
  • Dielectric grease

Step 1

Remove the engine cover as pictured. Simply lift firmly upwards.

Step 2

Here you can see the four spark plug coil packs we need to remove.

Step 3

Each has two torx bolts holding the coil pack in place. Use an E8 socket to remove these.

Step 4

As required you may need to unplug the coil pack or unplug neighbouring looms. Don’t forget to reconnect these later on.

Step 5

Lift up and remove the coil pack.

Step 6

We will now remove the spark plugs. Push the spark plug socket firmly onto the spark plug to engage it. Using an extension bar and ratchet, remove the spark plug.

Step 7

Here we have a comparison between the new and old spark plugs. The old spark plug travelled 60,000km.

Step 8

It’s time to install the new spark plug. Apply even coverage of aluminium grade anti-seize and insert the spark plug into the engine. Engage the threads by hand to ensure they are not cross threaded.

Step 9

Using a torque wrench, tighten the spark plug to 25nm.

Step 10

Apply a small amount of dielectric grease into the coil pack and spread onto the metal terminal with a toothpick.

Step 11

Reinstall the coil packs and hand tighten the bolts. You may feel some resistance when reinstalling, this is normal.

Step 12

Repeat this process for all four spark plugs.

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