2018 RX 350 Rough Idle and Misfire - CEL On

ClearTheCode guidance (Lexus · Engine & drivetrain)

Summary: For 2018 RX 350 Rough Idle and Misfire - CEL On, 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've got a 2018 Lexus RX 350 F Sport with about 75,000 miles. Lately, it's been idling really rough, especially when cold. The check engine light came on yesterday, and it feels like it's misfiring.

I haven't noticed any significant loss of power while driving, but the vibration at stops is getting annoying. I'm worried about potential damage if I keep driving it like this.

Any ide…

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