P0301
Cylinder 1 Misfire Detected
Ignition / misfire
Generic OBD-II
High
What it means
P0301 means the engine control module has detected a misfire specifically in cylinder 1 — fuel isn't burning properly there, so the engine runs rough and loses a bit of power. It's usually an ignition or fuel-delivery fault on that one cylinder, and sustained misfiring can damage the catalytic converter, so it's worth fixing promptly.
High
Can I keep driving? Drivable short distances, but a flashing check-engine light means an active misfire — keep driving to a minimum until it's fixed to protect the catalytic converter.
Common symptoms
What you'll notice
- Check-engine light on (may flash during an active misfire)
- Rough idle, shaking, or stumbling
- Hesitation and reduced power on acceleration
- Increased fuel consumption
Common causes
Most likely first
- Worn or fouled spark plug in cylinder 1Likely
- Failed ignition coil or plug wire on cylinder 1Common
- Clogged or leaking fuel injector on cylinder 1Common
- Vacuum leak affecting cylinder 1Less often
- Low compression in cylinder 1 (valve or ring wear)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data to confirm the misfire is isolated to cylinder 1.
- Inspect and replace the cylinder 1 spark plug — the cheapest and most common cause.
- Swap the cylinder 1 coil with a neighbouring cylinder; if the misfire follows the coil, replace it.
- Test the cylinder 1 injector and check for vacuum leaks near that runner.
- If it persists, run a compression test on cylinder 1 for a mechanical fault. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0301?+
Only briefly. A single-cylinder misfire dumps unburned fuel into the exhaust and can overheat the catalytic converter — worse if the light is flashing.
Can I just clear P0301?+
You can, but it returns within a few drive cycles unless the cause on cylinder 1 is repaired.
Related codes
Often seen with P0301
Read & clear P0301 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX