Infiniti introduced the I30 car model in 1996. All I30's have an onboard diagnostic (OBD) computer installed. When the OBD detects a problem with your Infiniti I30, a "Check Engine" signal lights up on the dashboard to let you know a system is malfunctioning. A scan with an OBD auto diagnostic scanner will tell you what problems the car's computer has found in a system. The scanner downloads a code that is matched against the troubleshooting codes found in the owner's manual to diagnose the faulty system so it can be serviced, repaired or replaced as needed.
Remove the cover from the Infiniti I30's fuse box located under the driver's side dashboard. Find the OBD computer port in the fuse box. It is a multiple-pin port that the auto diagnostic scanner plugs into. Plug the end of the scanner into the port and turn the key to the right but do not start the engine. The plug on the scanner should attach to the port easily. If it does not slide right in, back it out and start over. An OBD scanner for the Infiniti I30 is available at auto parts stores or online.
Turn on the diagnostic tool per the manufacturer's instructions and wait for the trouble code to download on the scanner. The scanner tells you when the code is read and downloaded.
Unplug the tool from the port by pulling it straight out and put the fuse box cover back in place. Scroll down on the menu on the diagnostic tool to where it says "Retrieve Code" and retrieve the trouble code stored in the scanner. The code indicates the problem with the car as diagnosed by the OBD computer.
Find the appropriate code listed in your Infiniti I30 owner's manual to determine what the problem is with your Infiniti. Repair and/or replace the faulty components on your vehicle as needed.
