How do I know which spark plug is bad or still okay for use? - Automotive Q and A

One way to determine if a spark plug is bad is to check for physical damage such as cracks or broken pieces.

Another way is to conduct a spark plug test using a spark plug tester tool to see if the plug is producing a spark.

Additionally, if the engine is running poorly or there are misfires, it could be an indication of a bad spark plug.

It's recommended to replace spark plugs every 30,000 to 50,000 miles as part of routine maintenance.

* For more understanding about Spark Plugs, consult an auto mechanic.