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Focus ST · Reliability

Focus ST Spark plugs

Your Focus ST

Pick your year to see what fits.

Every US Focus ST (2013–2018) is a hatchback with a 6-speed manual and the same 2.0L EcoBoost engine, so the same parts fit every year.

Restores lost power
Easy$40–$6030–45 min
All Focus ST mods

Why do it

Turbo engines are hard on spark plugs. Fresh plugs gapped right keep the power you paid for, and a tuned car needs plugs one step colder.

Tools you'll need

Parts to buy

Double-check fitment before buying.

Before you start

  • Pick your plugs: the NGK set one step colder (6510) if your car is tuned or has engine mods, or the NGK set in the factory heat range (6509) if it's stock.
  • Work on a cold engine. Turbo engines get very hot around the plugs.
  • Gap the new plugs to 0.030–0.032" before they go in. They come out of the box gapped wider than the Focus ST wants.

Video guide

Focus ST NGK Iridium IX spark plug install
by CJ Pony Parts on YouTube

The same NGK one-step-colder set we list. His car has an aftermarket intake, which is why he moves a pipe first.

Watch the whole video

Steps

  1. Remove the engine cover

    • Pull the plastic engine cover straight up off its rubber mounts.
    • The four coils sit in a row underneath, one on top of each spark plug.
    Watch this step (1:00–1:15)

  2. Move the intake pipe out of the way

    • Look at whether the intake pipe sits over the coil bolts. In the video an aftermarket intake covers them.
    • If it does, loosen the hose clamp, remove the two mounting screws and pull the rubber sleeve off so you can push the pipe back far enough to reach the bolts.
    Watch this step (1:15–1:45)

  3. Remove one coil

    • Work on one cylinder at a time. Lift the wiring harness a little so you can reach the coil's 8mm bolt with a 1/4" ratchet.
    • Unplug the coil, remove the bolt, then give the coil a small twist and pull it straight up.
    Watch this step (1:45–2:15)

  4. Remove the old plug

    • Blow any dirt out of the plug well first so nothing falls into the engine.
    • Use a 5/8" spark plug socket (or a 5/8" deep socket) on a 6" extension to loosen the plug and lift it out.
    Watch this step (2:11–2:28)

  5. Gap and install the new plug

    • Check the gap with your gap tool and set it to 0.030–0.032". Bend only the outer electrode, never the iridium tip.
    • Put a little anti-seize on the threads, start the plug by hand until it seats, then torque it to the spec on the box or in your service manual.

    Tip: If the plug won't turn easily by hand, back it out and start again. A cross-threaded plug can ruin the cylinder head.

    Watch this step (2:28–2:48)

  6. Refit the coil and repeat

    • Push the coil down until it seats, refit its 8mm bolt and plug it back in.
    • Repeat for the other three cylinders.
    Watch this step (2:48–3:20)

  7. Reassemble and test

    • Refit the intake pipe and its clamp, then the engine cover.
    • Start the engine. It should idle smoothly with no flashing check-engine light.
    Watch this step (3:09–3:43)

How to know it worked

Did this guide work for you?

Safety first

  • Park on flat ground, set the parking brake and chock the wheels.
  • Never get under a car held up only by a jack. Use jack stands.
  • Let the engine and exhaust cool first.
  • Disconnect the battery before unplugging electrical parts.
  • Wear safety glasses.
  • If something doesn't match your car, stop and ask a shop.

Follow your part's instructions and your service manual's torque specs.