2002 Chevy Suburban P0308 Code: Diagnosis and Fix After Replacing Plugs, Coils, and Wires
I own a 2002 Chevrolet Suburban that has been throwing up a P0308 diagnostic trouble code with the SES (Service Engine Soon) light activated. I've already replaced the spark plug, ignition wires, and coil pack for cylinder #8, but the issue persists. The SES light turns off temporarily and the vehicle runs smoothly for about two days before returning to the same problem—recurring every few days. What could be causing this intermittent misfire? Is there a deeper underlying issue I should investigate beyond basic component replacement?
Start with simple, low-cost troubleshooting steps: - Add one bottle of Seafoam or Techron fuel system cleaner to the tank. - Confirm you're using AC Delco spark plugs—some aftermarket brands can cause misfires. - Verify that cylinder #8 is actually firing by checking the plug condition: look for wetness, dryness, black soot, or tan deposits. This gives the fuel injector and cleaning agents time to work. If there's no improvement after several days of consistent use, consider moving on to more advanced diagnostics.