How Do You Know the Size Gap for the Spark Plugs in Your Car?

A gap gauge is used to ensure the proper gap size when installing new spark plugs in a vehicle; to find the proper gap size, refer to the vehicle's manual or the specification decal found under the hood. If the gap size is not set properly, the engine loses power and the vehicle loses fuel efficiency.

Changing spark plugs is a regular part of a vehicle's maintenance and takes under an hour to do without the assistance of a professional mechanic. The instructions below show how to change the spark plugs.

Tools Needed

  • 3/8-inch rachet
  • Ratchet extensions
  • Spark plug gap gauge
  • Spark plug socket
  • 3/8-inch swivel socket
  • Compressed air canister
  1. Prepare the vehicle
  2. Turn the engine off and allow it to cool. Make sure the proper spark plugs have been purchased according to the vehicle's manual.

  3. Disconnect the spark plug
  4. Disconnect the spark plug wire one plug at a time to ensure the wires match correctly when reinstalling.

  5. Clean the area
  6. Wear eye protection while spraying the area with compressed air to clean any debris from the area.

  7. Remove the spark plug
  8. Turn the spark plug counter clockwise with the spark plug ratchet to loosen. Remove the spark plug by hand once it is loosened.

  9. Gauge the gap
  10. Use the spark plug gap gauge to determine the proper gap according to the vehicle's manual.

  11. Insert new spark plugs
  12. Make sure the new spark plug is free of any dirt or debris before installing it. Screw the spark plug into place by hand first and then use the ratchet to tighten and secure it.

  13. Attach the wire
  14. Reattach the spark plug wire to the new plug. Use a twisting motion to seat the boot above the plug until a click is heard.

  15. Repeat for remaining plugs
  16. Repeat the steps until all the spark plugs have been removed and replaced.