P0306 Code: Cylinder 6 Misfire Detected
The engine computer has detected misfires specifically in cylinder 6 — that cylinder is not firing cleanly while the others are.
What this means for driving
Same posture as other single-cylinder misfires: prompt attention is warranted because unburned fuel can damage the catalytic converter. A flashing check-engine light, severe shaking, or sharp power loss means stop and arrange a tow.
When in doubt, have a mechanic assess it promptly. If any of the red-flag symptoms below are present, stop driving and arrange a tow rather than risking it.
Important: This page is general information only — not professional mechanical advice and not a diagnosis for your specific vehicle. Fault causes and severity vary by make, model, year, and condition. A qualified mechanic should confirm any diagnosis before you make driving decisions or authorize repairs.
Red-flag symptoms: stop and get help
- Check-engine light flashing
- Severe shaking or major loss of power
- Strong fuel smell from the exhaust
- Engine stalling repeatedly
Symptoms of P0306
- Rough idle or vibration
- Hesitation on acceleration
- Loss of power
- Poor fuel economy
- Check-engine light on or flashing
Most likely causes, ranked
- Worn or fouled spark plug in cylinder 6
- Failing ignition coil on cylinder 6
- Clogged or faulty fuel injector for cylinder 6
- Vacuum leak near cylinder 6's intake runner
- Low compression in cylinder 6
How a mechanic diagnoses it
- Plug and coil for cylinder 6 inspected, with a coil swap to test whether the misfire moves.
- Injector tested; compression test if ignition and fuel check out.
Likely fixes
- Replace spark plug(s) (DIY)
- Replace ignition coil (cylinder 6)
- Replace fuel injector (cylinder 6)
- Repair vacuum leak
Repair costs vary by vehicle, region and shop. Get a quote from a local mechanic.
Related codes
- P0300: Random/Multiple Cylinder Misfire Detected
- P0305: Cylinder 5 Misfire Detected
- P0301: Cylinder 1 Misfire Detected
CheckMyCarCode content is general information only and is not a substitute for professional diagnosis. Trouble-code meanings are standardized for generic (P0xxx) codes, but causes, severity, and repairs vary by vehicle. If your car shows a red-flag symptom, stop driving and get professional help.