The Lemon IndexCylinder 4 is not firing properly, so the engine runs rough and loses some power. Full P0304 page
16 owner complaints · one of 159 codes Ford Fusion owners name · 4% of Ford Fusion complaints that name a code (every car: 2.4%)
Middle of 101,000 miles · most between 87,000 and 103,000 (7 owners gave it)
Ford Fusion owners named P0304 in 16 complaints to the U.S. government (NHTSA), most often on the 2016, 2019 and 2015 model years, at a middle of 101,000 miles. The part they name most is the head gasket (12 complaints). Complaints are owner reports, not proof of a defect.
Ford Fusion model years that report P0304
Owner complaints naming P0304, by model year. Raw counts: years that sold more get more complaints, so this is each model year's record, not a failure rate.
Mileage when it happened
101,000 miles is the middle of what 7 owners entered. Half were between 87,000 and 103,000 miles.
The mileage on the complaint form, when the owner gave one.
What owners say caused it or fixed it
The most-named part is the head gasket, in 12 of the 16 complaints (75%). 7 of those mention it being replaced or repaired, and 3 say the problem came back afterwards. Next: engine (replaced or rebuilt) (9), spark plugs (5) and ignition coils (2).
- Head gasket or coolant in a cylinder12 complaints7 mention a repair or replacement, 3 of them say the problem came back · what Ford Fusion owners paid
- Engine replaced or rebuilt9 complaints9 mention a repair or replacement, 2 of them say the problem came back · what Ford Fusion owners paid
- Spark plugs5 complaints5 mention a repair or replacement, 3 of them say the problem came back · what owners paid
- Ignition coils2 complaints2 mention a repair or replacement, 2 of them say the problem came back · what Ford Fusion owners paid
4 complaints mention a recall.
Counted from the owners' own words: a part counts when a sentence names it with a cause or repair word. What owners wrote, not a diagnosis. A shop should confirm the cause before replacing parts.
Symptoms owners describe with P0304
81% of these complaints say the check engine light came on.
- Shakes, runs rough or misfires75%12 of 16 complaints
- Overheats50%8 of 16 complaints
- Flashing check engine light12%2 of 16 complaints
- Transmission slips or shifts hard12%2 of 16 complaints
- Stalls or shuts off12%2 of 16 complaints
Share of the complaints naming P0304 whose text also describes each problem. A complaint can describe more than one.
Codes owners report with it
P0301 8 P0300 8 P0316 7 P1285 5 P1299 5 P0217 5
Other codes named in the same Ford Fusion complaints, and in how many.
Repair costs
Ford Fusion head gasket replacement cost · Ford Fusion engine replacement cost · Ford Fusion ignition coil replacement cost
Recalls on these Ford Fusion years
- Engine · 2013 · issued 2017
If the vehicle is started and driven with an insufficient level of coolant within the engine cooling system, the engine cylinder head may overheat, crack and leak oil. NHTSA 17V209000 - Engine · 2013 · issued 2012
Coolant system leaks may cause the engines to overheat and leak flammable engine fluids. NHTSA 12V551000
2 recalls for the same systems (engine) on the Ford Fusion model years above. A recall for the same system isn't proof it's behind P0304. Recall work is free at any dealer: check a VIN at nhtsa.gov/recalls or with our VIN check.
Keep going
- P0304: meaning, causes and every car that reports it
- Ford Fusion reliability by year
- 2016 Ford Fusion problems and recalls
Other codes Ford Fusion owners report
P2111 P2112 P0302 P1450 U3000 P0301 P0303 P0300 C1277 P0316
P0304 on other cars
Ford Escape (49) · Ford Edge (31) · Honda CR-V (23) · Honda Accord (20) · Honda Odyssey (19) · Honda Pilot (14) · Kia Sorento (10)
The details
How we count
We read every owner complaint in the NHTSA file whose text names this trouble code, and count the ones filed about this model (matched by the make, model and model year on the complaint). Mileage is what the owner entered on the form.
Parts: a complaint counts for a part when one of the owner's own sentences names that part together with a cause word (failed, bad, diagnosed, caused by, leaking ...) or a repair word (replaced, repaired, new, reprogrammed ...). "Came back" means the same complaint also says the problem returned or the repair didn't fix it. These are counts of what owners wrote, not a diagnosis, and one complaint can name several parts.
Complaints are reports, not proof of a defect, and most owners never file one. Popular models get more complaints, so the counts are not a failure rate. The code meaning is the standard SAE J2012 definition in our own words, or the carmaker's meaning where we verified it for that make.
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.
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
- Fuel injector on cylinder 4
- Vacuum leak near that cylinder
- Low compression (valve or piston ring problem)
Check the complaints yourself
NHTSA complaint numbers (search them at nhtsa.gov): 11747790, 11681840, 11672866, 11650523, 11649929, 11625213, 11620471, 11609723, 11519433, 11497725, 11461286, 11404251 and 4 more.
Quick answers
What does P0304 mean on a Ford Fusion?
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.
Which Ford Fusion years have the most P0304 complaints?
In complaints to NHTSA, owners of the 2016 (5), 2019 (4), 2015 (3) Ford Fusion named P0304 most (16 complaints in all, 2013–2019). Raw counts, not a failure rate.
What fixes P0304 on a Ford Fusion?
Owners most often name the head gasket (12 of 16 complaints), then engine (replaced or rebuilt) and spark plugs. That's what owners wrote, not a diagnosis: have a shop confirm the cause with a scan and tests before replacing parts.
At what mileage does P0304 show up on a Ford Fusion?
Owners who gave their mileage reported a middle of 101,000 miles; half were between 87,000 and 103,000 (7 owners).
Can I drive my Ford Fusion 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.
Sources: NHTSA owner complaints that name P0304 on the Ford Fusion, counted by The Lemon Index; NHTSA recalls; repair bills owners named. Meanings: SAE J2012 in our own words. Owner reports, not a diagnosis or repair advice for your car.