OBD-II code · Powertrain (generic)
P0309 Cylinder 9 Misfire Detected
Misfires concentrated on cylinder 9. A cylinder-specific code points away from shared causes (fuel pressure, MAF) toward components dedicated to that cylinder — coil, spark plug, injector, compression.
Is it safe to drive with P0309?
Drive gently and get it checked soon. If the check-engine light is flashing, stop driving: a severe misfire can overheat and ruin the catalytic converter.
Common causes
- Most likelyIgnition coil failed
Symptoms
- Check engine light on or flashing
- Rough idle and uneven running
- Power loss, hesitation under acceleration
- Increased fuel consumption
- Possible smell of unburned fuel from exhaust
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.3–2 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Ignition Coil, Spark Plug
Related codes
- P0300Random/Multiple Cylinder Misfire Detected
- P0301Cylinder 1 Misfire Detected
- P0302Cylinder 2 Misfire Detected
- P0303Cylinder 3 Misfire Detected
- P0304Cylinder 4 Misfire Detected
- P0305Cylinder 5 Misfire Detected
- P0306Cylinder 6 Misfire Detected
- P0307Cylinder 7 Misfire Detected
- P0308Cylinder 8 Misfire Detected
- P0310Cylinder 10 Misfire Detected
- P0311Cylinder 11 Misfire Detected
- P0312Cylinder 12 Misfire Detected
- P030AIgnition A Control Signal Circuit/Open
- P030BIgnition A Control Signal Circuit Low
- P030CIgnition A Control Signal Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.