OBD codes / P0303
P0303
SeriousCylinder 3 Misfire Detected
Address promptly — can worsen or affect drivability.
Likely causes
- bad plug/coil cyl 3
- injector
- low compression
Common fixes
- swap coil to confirm
- replace plug
Seeing P0303 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0303 for my vehicleGeneric OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.