P0304
Cylinder 4 Misfire Detected
Your engine's computer has detected that cylinder number 4 is not firing correctly, meaning it's not contributing power as it should.
The powertrain control module (PCM) has detected a misfire condition in cylinder number 4.
Common causes
- high
Faulty Spark Plug (Cylinder 4)
A worn, fouled, or damaged spark plug in cylinder 4 is a very common cause of a single-cylinder misfire.
Typical part cost: $10-30
- high
Faulty Ignition Coil or Wire (Cylinder 4)
A failing ignition coil or damaged spark plug wire specific to cylinder 4 will prevent proper spark delivery.
Typical part cost: $50-200
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First things to check
- 1Swap spark plug from cylinder 4 to another cylinder and see if the misfire moves.
- 2Swap ignition coil from cylinder 4 to another cylinder and see if the misfire moves.
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Related codes
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Frequently asked questions
What's the most common fix for a P0304?
The most common and often easiest fix is replacing the spark plug and/or ignition coil for cylinder 4. These components are wear items and frequently fail, leading to misfires.
Can a P0304 code be caused by a bad mass air flow (MAF) sensor?
While a bad MAF sensor can cause general engine performance issues and sometimes P0300 (multiple misfires) due to incorrect air measurement, it's less likely to cause a misfire specifically in cylinder 4 unless there's an additional, localized problem.
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