2018 Challenger R/T - P0304 Misfire and Rough Idle

ClearTheCode guidance (Dodge · Diagnostics & codes)

Summary: For 2018 Challenger R/T - P0304 Misfire and Rough Idle, work through these steps on your 2016+ vehicle:

1. Confirm the symptom — note when it happens (cold start, highway, after fuel fill, etc.).
2. Scan codes — save all pending/stored DTCs; don't clear until you've recorded them.
3. Check TSBs & recalls — look up your VIN for open campaigns and known fixes.
4. Inspect the obvious — related fuses, connectors, fluid level, and recent repairs.
5. Test the common fix — follow model-specific service procedures; one change at a time.
6. Escalate if needed — burning smell, no brakes, overheating, or stalling in traffic → shop visit.

Owner reported: My 2018 Dodge Challenger R/T with the 5.7L HEMI has been acting up lately. The check engine light came on a few days ago, and it's been running really rough, especially at idle. It feels like it's shaking more than usual.

I hooked up my OBD-II scanner and pulled a P0304 code, which points to a misfire in cylinder 4. I'm wondering if it's just a spark plug, coil pack, or something more serious.

A…

This is educational guidance, not a substitute for hands-on diagnosis.