P0304: Cylinder 4 Misfire Detected
Short answer: P0304 means “Cylinder 4 Misfire Detected”. It is a standard OBD-II code, so the basic meaning is the same on every car. Below is what it means on each of the 6 cars we cover, with a link to the full page for each car.
Standard OBD-II code Same meaning on all cars (SAE J2012).
P0304 on each car
| Car | Meaning on this car | Confidence |
|---|---|---|
| Toyota Vitz (1st gen) | Misfire in cylinder 4 | medium |
| Toyota Corolla (11th gen, E170) | Cylinder 4 Misfire Detected | medium |
| Toyota Corolla (10th gen, E140) | Cylinder 4 Misfire Detected | medium |
| Honda City (5th gen, GM2) | Cylinder 4 Misfire Detected | medium |
| Honda Civic (10th gen, FC) | Cylinder 4 Misfire Detected | medium |
| Suzuki Wagon R (Pakistan, K10B) | Cylinder 4 Misfire Detected | medium |
Symptoms
- Check engine light on
- The engine may be harder to start
- The engine may stumble / stumble, and/or hesitate
Likely causes
- Faulty spark plug or wire
- Faulty coil (pack)
- Faulty oxygen sensor(s)
- Faulty fuel injector
- Burned exhaust valve
- Faulty catalytic converter(s)
- Running out of fuel
What to check, in order
- Read the code and freeze-frame data with an OBD-II scanner
- Check the connector and wiring of the part named in the code
- Test the part with scanner live data or a multimeter, using the values in the repair manual
- Fix the cause, clear the code and test-drive
Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.