Cylinder 1 Misfire Detected
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.
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
Appears alongside · share of P0301 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.
P0301 by make
Based on commonly reported failure patterns across owner and repair communities, not on our scan data.
BMW
On BMWs, failing ignition coils and worn spark plugs are a common reason for a misfire on cylinder 1, particularly on turbocharged engines. Replace plugs and check the coils together.
Chevrolet
On Chevrolet V8 trucks and SUVs with Active Fuel Management, cylinders 1, 4, 6 and 7 are the ones that shut off to save fuel, and worn lifters on those cylinders are a commonly reported cause of misfires. A ticking noise along with this code is worth getting checked soon.
Dodge
On Dodge cars and SUVs with the 5.7L Hemi and cylinder-deactivation, cylinders 1, 4, 6 and 7 are the ones that shut off, and worn lifters on those cylinders are a commonly reported cause of misfires. A ticking noise along with this code is worth getting checked soon.
Ford
On Ford engines with coil-on-plug ignition, such as the 5.4L Triton, a failing coil or worn spark plug on cylinder 1 is a commonly reported cause. Swapping the coil with a neighbouring cylinder is an easy way to see if the misfire follows it.
GMC
On GMC V8 trucks and SUVs with Active Fuel Management, cylinders 1, 4, 6 and 7 are the ones that shut off to save fuel, and worn lifters on those cylinders are a commonly reported cause of misfires. A ticking noise along with this code is worth getting checked soon.
Honda
On Hondas, a worn plug or coil on cylinder 1 is common, and on V6 models with cylinder deactivation, fouled plugs from oil can also play a part. Check the plug condition before swapping parts.
Hyundai
On Hyundai models, a misfire on cylinder 1 can be a simple coil or plug problem, but on 2.4L four-cylinder engines it can also be a sign of internal engine wear. Get it checked soon if there is knocking or oil use.
Jeep
On Jeeps with the 5.7L Hemi and cylinder-deactivation, cylinders 1, 4, 6 and 7 are the ones that shut off, and worn lifters on those cylinders are a commonly reported cause of misfires. A ticking noise along with this code is worth getting checked soon.
Kia
On Kia models, a misfire on cylinder 1 can be a simple coil or plug problem, but on 2.4L four-cylinder engines it can also be a sign of internal engine wear. Get it checked soon if there is knocking or oil use.
Nissan
On Nissans, ignition coils and spark plugs on cylinder 1 are the usual culprits, particularly on V6 models. Swap coils between cylinders to see if the misfire follows.
Ram
On Ram trucks with the 5.7L Hemi and cylinder-deactivation, cylinders 1, 4, 6 and 7 are the ones that shut off, and worn lifters on those cylinders are a commonly reported cause of misfires. A ticking noise along with this code is worth getting checked soon.
Subaru
On Subarus, plugs and coils on cylinder 1 are the first things to check. On older 2.5L boxer engines, a head gasket leak into a cylinder can also cause misfires.
Toyota
On Toyotas, a failed ignition coil or worn spark plug on cylinder 1 is the usual cause. Swapping the coil with a neighbouring cylinder shows quickly whether the misfire moves.
Volkswagen
On VW and Audi turbo engines, a failing ignition coil on cylinder 1 is a very common cause. Swapping coils between cylinders is a cheap way to confirm it.
FAQ
Quick answers
Is it safe to drive with P0301?+
Can I just clear P0301?+
Related codes
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Read & clear P0301 yourself
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