[Component Inspection]

Check the spark plug for any damage on its thread and insulator.
If there is damage, replace the spark plug.
Check the electrode. Measure the insulation resistance with an ohmmeter.
If the resistance is less than the specified value, adjust the electrode gap.

Specification: 10 MΩ or more

Fig 1: Measuring Insulation Resistance Using Ohmmeter
Courtesy of KIA MOTORS AMERICA, INC.
Check the spark plug electrode gap.
If the gap is greater than the maximum, replace the spark plug.

Specification: 0.7 ~ 0.8 mm (0.028 ~ 0.031 in.)
NOTE:
- If adjusting the gap of a new spark plug, bend only the base of the ground electrode. Do not touch the tip. Never attempt to adjust the gap on a used plug.
Fig 2: Adjusting Gap Of Spark Plug
Courtesy of KIA MOTORS AMERICA, INC.