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Tools you need for spark plugs on a 2016-2021 Honda Civic

Easy · 45-90 minutes · Updated 2026-09-28
Must-have tools
  1. 14 mm thin-wall magnetic spark plug socket
  2. 3/8 in ratchet with 6 in extension
  3. 3/8 in torque wrench, 5-25 ft-lb
  4. 10 mm socket, 3/8 in drive

On the 10th-gen Civic this is one of the easiest jobs on the car. All four coil-on-plug coils sit right on top of the valve cover, so you remove the plastic cover, pull four connectors and four bolts, and the plugs are straight down in the tubes. The 2.0L K20C2 is the more open of the two; the 1.5L turbo L15B7 has intake and charge piping plus a harness running across the valve cover that you need to move first, which adds maybe 20 minutes.

The things people get wrong: doing it warm, and over-torquing. The head is aluminum and 13 ft-lb feels loose if you are used to guessing, but that is the spec. Always start plugs by hand with the socket on a bare extension so you feel the threads engage, and never try to re-gap the factory iridium plugs.

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Complete tool and parts list

ItemType
Socket wrench set
3/8 in drive ratchet
Drives all the covers, coil bolts and plug socket.
Requiredshop
Socket
10 mm, 3/8 in drive
Engine cover bolts, intake duct bracket and coil retaining bolts.
Requiredshop
Socket
8 mm, 1/4 in drive
Some 1.5T coil and bracket fasteners are 8 mm.
Recommendedshop
Extension set
3/8 in drive, 3 in and 6 in
Reaches the plugs down in the valve cover tubes.
Requiredshop
Spark plug socket
14 mm (9/16 in) thin-wall, magnetic or rubber insert, 3/8 in drive
Only a thin-wall plug socket fits the narrow plug tubes and holds the plug for install.
Requiredshop
Swivel/wobble extension or universal joint
3/8 in drive
Helps clear the 1.5T charge piping when lifting coils out.
Recommendedshop
Torque wrench
3/8 in drive, 5-25 ft-lb range
Plugs thread into aluminum head; 13 ft-lb must be set accurately.
Requiredshop
Flat trim tool / small pry tool
Plastic
Pops the coil connector locks and engine cover grommets without breaking them.
Recommendedshop
Hose clamp pliers or flat screwdriver
For spring/worm clamps on 1.5T intake piping
Loosens the intake duct that crosses over the 1.5T valve cover.
Recommendedshop
Compressed air or vacuum with nozzle

Blows dirt out of the plug wells before removing plugs.
Recommendedshop
Spark plug gap gauge
Wire-type
Only to verify factory gap (1.5T ~0.9 mm, 2.0L ~1.1 mm); never bend iridium tips.
Recommendedshop
Spark plugs
1.5T L15B7: NGK DILZKAR7A9 (Honda 12290-59B-003); 2.0L K20C2: NGK ILZKAR7B11 (verify by VIN)
The replacement plugs — use OEM-spec iridium only.
Partsshop
Dielectric grease
Silicone
Thin film inside the coil boot to prevent sticking and arcing.
Consumablesshop
Anti-seize
Nickel, optional and very sparing
Optional trace on threads only; Honda plugs come pre-plated so most techs skip it.
Consumablesshop
Shop rags

Keeps debris out of open plug holes.
Consumablesshop
Mechanic's gloves

Engine must be cool, but protects hands on tight metal edges.
Safetyshop

Differences within the 2016-2021 generation

Both engines use the same 14 mm (9/16 in) thin-wall plug socket and 13 ft-lb plug torque. Coil and cover bolts are 10 mm on the 2.0L; the 1.5T uses a mix of 10 mm and 8 mm and additionally requires removing the intake duct/charge pipe over the valve cover. Plug part numbers differ: NGK DILZKAR7A9-type for the 1.5T, ILZKAR7B11-type for the 2.0L.

Torque specs

Spark plug (both engines)13 ft-lb (18 Nm)
Ignition coil mounting bolt7 ft-lb (9.8 Nm)
Engine cover / intake duct 10 mm bolts7 ft-lb (9.8 Nm)

How the job goes

  1. Work on a fully cold engine. Aluminum heads and hot plugs are a bad mix, and cold threads pull out less.
  2. Disconnect the negative battery terminal if you want to avoid any chance of a stored misfire code (optional; no relearn required on this generation).
  3. Remove the plastic engine cover: on the 2.0L it lifts off rubber grommets after removing the visible 10 mm bolts; on the 1.5T remove the cover and then the intake duct/charge pipe crossing the valve cover (hose clamp plus one or two 10 mm bracket bolts).
  4. Unclip the coil harness from its retainers and lay it aside. Press the red or black lock tab and pull each coil connector straight off — do not pull on the wires.
  5. Remove the single 10 mm (some 8 mm) bolt from each ignition coil, twist the coil slightly to break the boot loose, and pull it straight up. Keep the coils in cylinder order.
  6. Blow or vacuum dirt out of each plug well so nothing falls into the cylinder.
  7. Using the thin-wall 14 mm plug socket with an extension, break each plug loose and remove it. Compare the old plugs for unusual wear, oil or fuel fouling before discarding.
  8. Check the new plugs visually; confirm the gap with a wire gauge but do not adjust iridium plugs. Wipe threads clean.
  9. Start each new plug by hand using the plug socket on an extension alone (no ratchet) so you can feel cross-threading, then torque to 13 ft-lb (18 Nm).
  10. Put a thin smear of dielectric grease inside each coil boot, seat the coils fully, install the bolts at 7 ft-lb, and reconnect the connectors until they click.
  11. Reinstall the harness retainers, intake duct/charge pipe (make sure the clamp is tight — a loose 1.5T charge pipe causes a boost leak), and the engine cover.
  12. Reconnect the battery, start the engine, let it idle a minute and confirm smooth running with no misfire light.

Watch out

The 14 mm thin-wall plug socket, 10 mm fasteners and 18 Nm plug torque are correct for both 10th-gen engines, but confirm the exact plug part number for your VIN and model year at the parts counter, since Honda revised the 1.5T plug spec during this generation.

Frequently asked

How often should spark plugs be changed on a 10th-gen Civic?

Honda lists roughly 100,000 miles for the iridium plugs on both engines. Many 1.5T owners change them earlier, around 60,000-75,000 miles, especially if the car sees short trips or has a tune, because fouling and misfires show up sooner.

What size socket do I need for the spark plugs?

A 14 mm (9/16 in) thin-wall spark plug socket on a 3/8 in drive, with a 6 in extension. A standard-wall plug socket often will not fit down the valve cover tubes.

Do I have to remove the intake manifold on the 1.5 turbo?

No. You only need to remove the engine cover and loosen or unbolt the intake duct/charge pipe and harness that run across the top of the valve cover. The coils are accessible from above.

What is the spark plug torque on a 2016-2021 Civic?

13 ft-lb (18 Nm) for both the 2.0L and 1.5T. Torque coil bolts to about 7 ft-lb; do not use an impact on anything here.

Other jobs on the 2016-2021 Honda Civic

Oil ChangeFront Brake Pads and RotorsRear Brake Pads and RotorsBattery ReplacementAlternator ReplacementStarter ReplacementCoolant FlushSerpentine Belt ReplacementTire RotationHeadlight Bulb ReplacementWiper Blade ReplacementThermostat ReplacementFront Strut ReplacementCabin Air Filter ReplacementEngine Air Filter ReplacementTransmission Fluid ChangeFront Wheel Bearing ReplacementOxygen Sensor ReplacementWater Pump Replacement

Spark Plug Replacement on other vehicles

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