2002 Oldsmobile Alero P0304 Code: Troubleshooting and Fix Guide
I have a 2002 Oldsmobile Alero that recently triggered a P0304 diagnostic code. After a previous tune-up, I replaced the spark plugs and wires with a friend's assistance. Immediately after, the vehicle began exhibiting rough idling, misfiring, and bucking—symptoms I did not experience before. The mechanic couldn't identify the issue, so I purchased a diagnostic reader which confirmed the P0304 code (cylinder 4 misfire). My car is showing all classic signs of ignition or fuel system problems commonly associated with this fault code. Currently, several people are suggesting I replace the starter and other components, but I'm concerned about unnecessary repairs. I need reliable guidance on how to properly diagnose and fix a P0304 in a 2002 Oldsmobile Alero without over-replacing parts.
First, verify that AC Delco spark plugs were used—non-compliant or incorrect plugs can cause misfires. Check for crossed wires, especially in the ignition system. Ensure all spark plugs are firing properly, with special attention to cylinder #4. These steps should help identify and resolve the P030-4 issue before further component replacement.