Engine and gearbox (P)
P0304: Cylinder 4 Misfire Detected
The engine control unit has detected a misfire in cylinder 4. This means that cylinder 4 is not firing correctly, which can affect engine performance.
Checked by a licensed car technician · last reviewed 29 September 2026
Symptoms
- Rough idling
- Poor acceleration
- Increased fuel consumption
- Engine hesitation
- Check engine light on
Common causes
- Faulty spark plug
- Defective ignition coil
- Clogged or faulty injector
- Low compression in cylinder 4
How to check it yourself
- Inspect and replace spark plug in cylinder 4
- Swap ignition coil with another cylinder to test
- Check injector operation and balance
- Perform a compression test on cylinder 4
Can I keep driving?
The car can be driven, but it is advisable to fix the issue soon to avoid further damage.
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