2017 CT6 V6 Misfire & Rough Idle - P0304 Code

ClearTheCode guidance (Cadillac · Diagnostics & codes)

Summary: For 2017 CT6 V6 Misfire & Rough Idle - P0304 Code, 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: Hey everyone, I'm having a persistent issue with my 2017 Cadillac CT6, 3.6L V6. The check engine light came on last week, and the car started running really rough, especially at idle. It feels like it's shaking quite a bit.

I hooked up my OBD-II scanner and pulled a P0304 code, indicating a misfire on cylinder 4. I'm wondering if this is a common issue with these engines or if there's a specific …

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