P0304High urgency
Cylinder 4 Misfire Detected
Powertrain · Ignition
⛔ Avoid highway speeds — risk of catalytic converter damage.
What this means
Cylinder 4 is misfiring. On inline 4-cylinder engines, cylinder 4 is at the firewall end — a common misfire location due to heat exposure.
Likely causes
- Faulty spark plug cylinder 4Most common
- Failed ignition coil cylinder 4Most common
- Bad fuel injector cylinder 4Common
Estimated repair cost
Spark plug replacement$50 – $200
Ignition coil replacement$150 – $350
Fuel injector service$150 – $400
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Frequently asked questions
What does P0304 mean?
Cylinder 4 is misfiring. On inline 4-cylinder engines, cylinder 4 is at the firewall end — a common misfire location due to heat exposure.
Is P0304 serious?
Avoid highway speeds — risk of catalytic converter damage.
How much does it cost to fix P0304?
Repair costs for P0304 range from $50 – $200 depending on the root cause and your vehicle.
Can I drive with P0304?
No — this code indicates a serious issue. Stop driving and have the vehicle inspected immediately.