OBD
P0304
Cylinder 4 Misfire Detected
What it means
P0304 means Cylinder 4 Misfire Detected.
Check these first
- Faulty spark plug or ignition coil on cylinder 4
- Clogged or leaking injector on cylinder 4
- Vacuum leak at the cylinder 4 intake runner
- Low compression in cylinder 4
- Engine mechanical wear
What to do next
- Confirm cylinder 4 misfire counts with an OBD-II scanner
- Swap the ignition coil and spark plug to test if the fault follows
- Verify the fuel injector on cylinder 4
- Compression test cylinder 4
- Inspect for intake leaks at that runner
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.