P0301
Cylinder 1 Misfire Detected
high
i Description
The ECU has detected a misfire specifically in cylinder 1. A misfire means the fuel/air mixture in cylinder 1 is not igniting properly or at all, resulting in a loss of power from that cylinder.
? Common Causes
- Worn or fouled spark plug in cylinder 1
- Faulty ignition coil for cylinder 1
- Damaged spark plug wire/boot
- Faulty fuel injector for cylinder 1
- Low compression in cylinder 1 (head gasket, valve, or piston ring issue)
! Symptoms
- Check engine light (may flash)
- Engine vibration and rough running
- Loss of power
- Rough idle
- Exhaust popping
# Diagnostic Steps
- Remove and inspect spark plug from cylinder 1
- Swap ignition coil with another cylinder and see if misfire follows
- Test fuel injector for cylinder 1
- Perform compression test on cylinder 1
- Check spark plug wire resistance (if applicable)
⚙ Typical Fix
Replace the spark plug and/or ignition coil for cylinder 1.
Parts Needed
Spark plug, Ignition coil, Spark plug wire (if applicable)
Estimated Cost
$50-$400
↔ Related Codes
Q Frequently Asked Questions
If the light is flashing, no — pull over safely. A steady light means you can drive gently to a mechanic, but avoid heavy acceleration.
Yes. Spark plug and coil replacement on cylinder 1 is a common DIY job. Swap the coil with another cylinder first to confirm the coil is the issue.
Spark plug: $8-$20. Ignition coil: $40-$100. Mechanic labour: $50-$150.
☞ Learn More
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