Engine and gearbox (P)
P0303: Cylinder 3 Misfire Detected
The engine control unit has detected a misfire in cylinder 3. This can affect engine performance and fuel efficiency.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Rough idle
- Engine hesitation
- Reduced power
- Increased fuel consumption
Common causes
- Faulty spark plug
- Defective ignition coil
- Clogged or faulty injector
- Low cylinder compression
How to check it yourself
- Inspect and replace spark plug
- Swap ignition coil with another cylinder
- Check injector operation
- Perform a compression test
Can I keep driving?
The car can be driven, but prolonged driving with a misfire can damage the catalytic converter.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer