P0303
Cylinder 3 Misfire Detected
Powertrain · Generic (all makes)System: Ignition + Intake Air/Vacuum
Fix within days. Damage or fuel waste builds up.
Likely causes
- Bad spark plug or coil on cylinder 3
- Faulty cylinder 3 injector
- Intake leak near cylinder 3
- Low compression on cylinder 3
What to check first
Swap the cylinder 3 coil with a neighbor to see if the misfire follows it, then check the plug and injector.
Typical repair cost
$100 – $450
Independent-shop parts and labor for the usual fix. Your price depends on the actual cause and the vehicle.
Next step
General information, not a diagnosis of your vehicle. Repair costs are typical shop ranges, not quotes.