Mazda MX-5 Miata Sport 2007 Manual page 1471

Fig. 4: Inspecting Spark Plug
Courtesy of MAZDA MOTORS CORP.
RESISTANCE INSPECTION
1. Measure the resistance of the spark plug using a tester as shown in Fig. 5 .
If not within the specification, replace the spark plug.

Spark plug resistance [25°C {77°F}]
3.0-7.5 kilohms
2007 Mazda MX-5 Miata Sport
2007 ENGINE Ignition System - MX-5 Miata