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.

Real-world scan data

Seen in

12,193

scans in the past year

Found in

1.9%

of scans

3.4%

of scans that found faults

Appears alongside · share of P0301 scans

P0300in 76.0% of scans

P0302in 52.6% of scans

P0303in 51.4% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.