P0301: Cylinder 1 Misfire Detected
Updated November 12, 2026
The engine computer has detected that cylinder 1 isn't firing properly. Unlike P0300, the problem is pinned to one cylinder, which usually makes it easier to find.
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🔧 Want to check this yourself? An OBD2 scanner reads the code; models with live data also show the sensor readings used in the checks below. See code readers and scanners from $24.99 ↓ · Which scanner do I need?
Common causes
- A worn spark plug
- A failing ignition coil
- A clogged or failing fuel injector
- Low compression in that cylinder (valve or ring problem)
Code meanings can vary slightly by manufacturer. Use these as a starting point and confirm with your vehicle's service information or a mechanic before replacing parts.
Symptoms
- Rough idle or shaking
- Loss of power
- A flashing check engine light when the misfire is severe
Is it safe to drive?
If the check engine light is flashing, avoid driving: unburned fuel can overheat and ruin the catalytic converter. With a steady light, it's usually OK to drive gently to a shop, but fix it soon.
How to check it with a scanner
- Plug an OBD2 scanner into the port under the dashboard and read all stored codes and the freeze-frame data (the conditions when the code set).
- Swap the cylinder 1 coil with a neighboring cylinder. If the misfire moves (for example to P0302), the coil is bad.
- Inspect the spark plug for wear, oil or carbon.
- If the plug and coil are fine, check the injector and do a compression test.
- After a repair, clear the code and drive normally for a few days to confirm it doesn't come back.
A basic code reader shows the code; scanners with live data let you watch sensor readings, which is what you need for most of the checks above. See OBD2 scanners under $100.
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Questions
What does P0301 mean?
P0301 is the generic OBD2 code for "Cylinder 1 Misfire Detected." The engine computer has detected that cylinder 1 isn't firing properly. Unlike P0300, the problem is pinned to one cylinder, which usually makes it easier to find.
Is it safe to drive with P0301?
If the check engine light is flashing, avoid driving: unburned fuel can overheat and ruin the catalytic converter. With a steady light, it's usually OK to drive gently to a shop, but fix it soon.
How do I check P0301 myself?
Read the code and freeze-frame data with an OBD2 scanner, then: Swap the cylinder 1 coil with a neighboring cylinder. If the misfire moves (for example to P0302), the coil is bad. Inspect the spark plug for wear, oil or carbon. If the plug and coil are fine, check the injector and do a compression test.
Related codes
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