The Lemon IndexCylinder 4 is not firing properly, so the engine runs rough and loses some power.
Get it fixed soon. A few more days of normal driving is usually OK, but waiting can turn a small repair into a bigger one or a breakdown.
Spark plug or ignition coil on cylinder 4. Then: fuel injector on cylinder 4; vacuum leak near that cylinder.
Owners named P0304 in 366 complaints to the U.S. government, most often on the Ford Escape.
Models that report it most
Complaints that name P0304, by model. Raw counts, not a failure rate: popular models get more complaints. Tap a model for its years, mileage and what owners say fixed it.
P0304 by model: P0304 Ford Escape (49) · P0304 Ford Edge (31) · P0304 Honda CR-V (23) · P0304 Honda Accord (20) · P0304 Honda Odyssey (19) · P0304 Ford Fusion (16) · P0304 Honda Pilot (14) · P0304 Kia Sorento (10)
Years owners report it on most: 2017 Ford Escape · 2017 Ford Edge · 2017 Honda CR-V · 2018 Ford Escape · 2018 Honda Accord · 2016 Ford Edge
The details
What P0304 means
Cylinder 4 is not firing properly, so the engine runs rough and loses some power. A flashing check engine light means the misfire is serious enough to damage the catalytic converter, so slow down and get it checked right away.
Can I drive with P0304?
Get it fixed soon. A few more days of normal driving is usually OK, but waiting can turn a small repair into a bigger one or a breakdown.
74% of the owner complaints that name P0304 also say the car shakes, runs rough or misfires. A complaint can describe more than one problem, so this doesn't prove the code caused it.
Common causes of P0304
- Spark plug or ignition coil on cylinder 4
- Fuel injector on cylinder 4
- Vacuum leak near that cylinder
- Low compression (valve or piston ring problem)
A shop should confirm the cause with a scan and tests before replacing parts.
What owners describe
- Shakes, runs rough or misfires: 74% of complaints
- Loses power or goes into limp mode: 18% of complaints
- Stalls or shuts off: 17% of complaints
- Overheats: 12% of complaints
Share of complaints naming the code whose text also mentions each problem.
Model years that report P0304 most
2017 Ford Escape (22), 2017 Ford Edge (17), 2017 Honda CR-V (13), 2018 Ford Escape (13), 2018 Honda Accord (9), 2016 Ford Edge (9).
Related codes
P0303 P0305 P0302 P0306 P0301 P0307 P0300 P0308
Quick answers
What does P0304 mean?
Cylinder 4 Misfire Detected. Cylinder 4 is not firing properly, so the engine runs rough and loses some power. A flashing check engine light means the misfire is serious enough to damage the catalytic converter, so slow down and get it checked right away.
Can I drive with P0304?
Get it fixed soon. A few more days of normal driving is usually OK, but waiting can turn a small repair into a bigger one or a breakdown.
What causes P0304?
Spark plug or ignition coil on cylinder 4; Fuel injector on cylinder 4; Vacuum leak near that cylinder; Low compression (valve or piston ring problem).
Counts: NHTSA owner complaints whose text names P0304. A complaint is an owner's report, not a diagnosis. Meanings: the standard SAE J2012 definitions in our own words; manufacturer codes only where verified for that make. General information, not repair advice for your car.