P0301: Cylinder 1 Misfire Detected
GarageDex's OBD-II reference explains that code P0301 means "Cylinder 1 Misfire Detected" - Cylinder 1 specifically is misfiring - it is not burning its fuel/air charge properly.
High - get it diagnosed before driving much
Short trips to diagnosis on a steady light; a flashing light means stop - unburned fuel damages the converter.
Symptoms
- Rough idle, shudder
- Flashing check-engine light under load
- Loss of power
- Smell of raw fuel
Common causes (most to least likely)
- Bad spark plug or coil on cylinder 1
- Clogged/leaking injector on cylinder 1
- Vacuum leak near that cylinder
- Low compression on cylinder 1
How to fix P0301
- Swap the coil/plug from cyl 1 to another cylinder - if the misfire follows, that part is the culprit
- Replace the failed plug or coil
- Test the injector and compression if ignition checks out
Guidance only - confirm the cause with a scan before replacing parts. Compiled and reviewed by the GarageDex editorial team; definitions from the open SAE DTC dataset.
Tools & parts for P0301
Confirm the cause before you buy anything - a code points to a system, not a guaranteed part. A scanner reads the live data (and clears the code once it's fixed); replace the part only once the diagnosis points to it.
As an Amazon Associate we earn from qualifying purchases, at no extra cost to you.
Frequently asked
What does the P0301 code mean?
GarageDex's OBD-II reference explains that code P0301 means "Cylinder 1 Misfire Detected" - Cylinder 1 specifically is misfiring - it is not burning its fuel/air charge properly.
What are the symptoms of P0301?
Common symptoms: Rough idle, shudder; Flashing check-engine light under load; Loss of power; Smell of raw fuel.
What causes a P0301 code?
The common causes, most to least likely: Bad spark plug or coil on cylinder 1; Clogged/leaking injector on cylinder 1; Vacuum leak near that cylinder; Low compression on cylinder 1.
Is it safe to drive with a P0301 code?
Short trips to diagnosis on a steady light; a flashing light means stop - unburned fuel damages the converter.
How do I fix a P0301 code?
Swap the coil/plug from cyl 1 to another cylinder - if the misfire follows, that part is the culprit Replace the failed plug or coil Test the injector and compression if ignition checks out Confirm the cause with a scan before replacing parts.