The spark plug sensor tester by OK Spark is a remarkable diagnostic tool. Before using any OBDII tool, you should use this to spark tester. You will be able to find out if the vehicle is having a spark or electrical issue, or if it is a totally separate issue. This tool is very reliable, and is always accurate. OK Spark also has designed a unique fuel injection tester tool that can easily check for trouble in the fuel system of most makes and models.