Code
P0304
Ignition / Engine
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Most likely causes
- شمعة أو ملف تالف
- حاقن
Symptoms you may notice
- Rough idle
- Shaking
- Check engine light
- Loss of power
Checks to run
- Swap coil/plug to another cylinder
- Test injector and compression on cyl 4
Tools you may need
OBD-II scanner
Multimeter
Compression tester
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.