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Impreza · Power

Impreza Spark plugs

Your Impreza

Pick your year to see what fits.

This page covers the non-turbo Impreza, including the 2.5RS, Outback Sport and RS. The WRX and STI get their own page.

Restores lost power
Medium$40–$951–2 hrs
All Impreza mods

Why do it

Worn plugs cost power and throttle response. Fresh iridium plugs bring back the punch your engine had new, and they last for years.

Tools you'll need

Parts to buy

Double-check fitment before buying.

Before you start

  • You need 4 NGK DILKAR7B8 plugs. They come pre-gapped; don't bend the fine iridium tip.
  • Work on a cold engine. The driver's side is the tight side, so do it first while you're fresh.
  • You need 4 NGK SILZKAR7B11 plugs. They come gapped at 0.044"; check with a wire gap tool, never by bending the iridium tip.
  • Work on a cold engine.
  • You need 4 NGK BKR6EIX-11 plugs. Check the gap is about 0.043" (1.1mm) with a wire gap tool.
  • Work on a cold engine. Your plugs have plug wires instead of coil-on-plug; pull them by the boot, never the wire.
  • You need 4 NGK IFR6E-11 plugs. Check the gap with a wire gap tool against your owner's manual spec.
  • Work on a cold engine. Your plugs have plug wires instead of coil-on-plug; pull them by the boot, never the wire.

Steps

  1. Remove the intake tube

    • Pop the body clip with a trim tool, loosen the two hose clamps (8mm), and lift out the intake tube and the half of the airbox with the airflow sensor.
    Watch this step (Ryan & Emilee, on a 2017–2023 Impreza) (0:08–0:30)

  2. Remove the battery

    • Disconnect the negative terminal first, then the positive (10mm). Undo the tie-down (10mm, deep socket helps), unhook it from the tray and lift the battery out.
    Watch this step (0:30–2:48)

  3. Move the wiring bracket

    • Remove the bolts holding the wiring loom bracket on the driver's side (there's a second bolt a couple of inches behind the first) so the loom can move out of the way.
    Watch this step (2:48–3:06) Watch the second bolt (4:26–5:09)

  4. Unbolt the coils

    • Each coil is held by one 10mm bolt. Crack them loose with a short wobble extension; the back one is tight against the A/C line.
    • You can leave the coils plugged in and just let them hang.
    Watch this step (5:16–6:32)

  5. Pull the coils

    • Twist and pull each coil straight out. Check the bottom for oil; a little oil means a valve cover gasket is starting to leak.
    Watch this step (6:32–7:30)

  6. Remove the front plug

    • Use a 14mm deep socket on a long extension plus a short wobble. Unscrew the plug and pull it out with a magnet.
    Watch this step (7:56–8:43)

  7. Remove the back plug

    • The back driver's-side plug is the hardest. A 14mm deep socket, a 1/4" to 3/8" adapter and a 1/4" wobble extension gets it out.
    Watch this step (8:43–10:06)

  8. Do the passenger side

    • The passenger side has more room. Remove the coil bolts, pull the coils and remove both plugs the same way.
    Watch this step (10:06–12:31)

  9. Fit the new plugs and put everything back

    • Thread each new plug in by hand first so it can't cross-thread, then torque to the spec in your service manual. Don't overtighten.
    • Refit the coils and their bolts, the loom bracket, the battery (positive first, then negative) and the intake tube.

    Tip: Slip a short piece of rubber hose over the plug to start it by hand in the deep holes.

    Watch this step (13:18–15:28)

  10. Make room on top

    • Remove the intake tube and air box parts that sit over the coils, and move the battery out of the way on the driver's side.
    Watch this step (YOUCANIC, on a 2012–2016 Impreza) (0:00–1:34)

  11. Remove the passenger-side coils and plugs

    • Unplug each coil, remove its 10mm bolt and pull it out. Unscrew both plugs with the 14mm socket on a wobble extension.
    Watch this step (1:34–3:43)

  12. Install the new plugs

    • Thread each plug in by hand first, then torque it to the spec in your service manual. Refit the coils and plug them in.

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

    Watch this step (3:43–7:36)

  13. Do the driver's side

    • Same job on the driver's side; it's tighter, so take your time with the back plug.
    Watch this step (7:36–11:04)

  14. Reassemble

    • Refit the battery, air box and intake tube, then start the engine.
    Watch this step (11:04–12:37)

  15. Make room on the driver's side

    • Move the battery and intake parts that are in the way so you can see down to the front plug.
    Watch this step (Carsntoys, on a 2010 Impreza 2.5) (0:00–0:58)

  16. Swap the driver's front plug

    • Pull the wire off by its boot, unscrew the plug with the 5/8" socket, and thread the new one in by hand before torquing it.
    Watch this step (0:58–4:09)

  17. Swap the driver's rear plug

    • The rear plug is tight against the body. A swivel joint between the socket and extension makes the angle work.
    Watch this step (4:09–6:04)

  18. Make room on the passenger side

    • Move the air intake parts on the passenger side out of the way.
    Watch this step (6:04–7:31)

  19. Swap the passenger plugs

    • Do both passenger-side plugs the same way, refit the wires until they click, and put everything back.
    Watch this step (7:31–10:49)

  20. Make room on the driver's side

    • Move the battery and intake parts that are in the way so you can see down to the front plug.
    Watch this step (Carsntoys, on a later Impreza; your 1.8L comes apart the same way) (0:00–0:58)

  21. Swap the driver's front plug

    • Pull the wire off by its boot, unscrew the plug with the 5/8" socket, and thread the new one in by hand before torquing it.
    Watch this step (0:58–4:09)

  22. Swap the driver's rear plug

    • The rear plug is tight against the body. A swivel joint between the socket and extension makes the angle work.
    Watch this step (4:09–6:04)

  23. Make room on the passenger side

    • Move the air intake parts on the passenger side out of the way.
    Watch this step (6:04–7:31)

  24. Swap the passenger plugs

    • Do both passenger-side plugs the same way, refit the wires until they click, and put everything back.
    Watch this step (7:31–10:49)

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.