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P0301 Cylinder 1 Misfire Detected
What it means
The engine computer detected that cylinder 1 isn't firing properly. Because it's a single cylinder, the cause is usually a part specific to that cylinder (plug, coil, injector).
Severity: High
Can I drive it? If the check engine light is flashing, stop driving as soon as safely possible — misfires can overheat and destroy the catalytic converter. Steady light: drive gently and fix soon.
Common causes (most likely first)
- Worn or fouled spark plug in cylinder 1
- Faulty ignition coil (or plug wire) on cylinder 1
- Clogged or failed fuel injector on cylinder 1
- Vacuum leak near that cylinder's intake port
- Low compression (valve or head gasket issue)
Likely fixes
- Swap cylinder 1's coil with a neighbor; if the misfire moves, replace the coil
- Inspect/replace spark plugs
- Test the injector
- Compression or leak-down test if parts check out
DIY parts cost
$15–$200
Approximate estimate
Shop repair cost
$100–$800+
Approximate estimate, parts + labor
DIY difficulty
Easy to Moderate
Varies by vehicle
Cost ranges are rough, approximate U.S. estimates and vary widely by vehicle, region, and parts brand. Always confirm the diagnosis before buying parts.
Parts you may need
- Spark plugsCheck price
- Ignition coilCheck price
- Spark plug wiresCheck price
- Fuel injectorCheck price
- Dielectric greaseCheck price
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