2012-2015 Honda Civic - Spark Plug Replacement

1

Cool the engine

Work only on a cold engine. Hot aluminum heads can pull threads when plugs are removed. Disconnect the negative battery terminal if required by your procedure.

2

Access the ignition coils

Remove any engine cover or intake tube blocking the coils. Label coil connectors or photograph their positions before unplugging.

3

Remove one coil at a time

Unplug the coil connector, remove the coil hold-down bolt, and pull the coil straight up. Work one cylinder at a time to avoid mixing parts.

4

Remove the old spark plug

Blow loose dirt from the well. Use a spark-plug socket with a rubber insert and extension to remove the plug. Inspect the tip for oil, coolant, or abnormal wear.

5

Gap and hand-thread the new plug

Confirm the new plug part number and set the gap to the manufacturer specification if required (many iridium plugs are pre-gapped). Start the plug by hand to avoid cross-threading.

6

Torque to specification

Torque the plug to the spec in the service information (typically a modest ft-lb or degree turn after seating). Do not overtighten — stripped head threads are expensive.

7

Reinstall the coil

Press the coil fully onto the plug, reinstall the hold-down bolt to snug/spec, and reconnect the electrical connector until it clicks.

8

Reassemble and test

Refit covers/intake components, reconnect the battery if removed, and start the engine. Listen for misfires and confirm a smooth idle. Clear any residual codes if a light remains.