Misfires
P0301
Cylinder 1 Misfire Detected
What does P0301 mean?
P0301 means cylinder 1 specifically is misfiring — combustion in that one cylinder is failing or incomplete. Because the fault is isolated to a single cylinder rather than wandering, the cause is usually a part belonging to that cylinder: its spark plug, its ignition coil, its injector, or its compression.
Can I keep driving with P0301?
High urgency
Same rule as P0300 — a flashing light means stop driving, because raw fuel reaching a hot catalytic converter can ruin it in minutes.
Symptoms of P0301
Rough idle and a vibration you can often feel through the car
Loss of power, especially under load
Flashing check engine light during an active misfire
Unburned fuel smell from the exhaust
Common causes of P0301
A worn or fouled spark plug in cylinder 1
A failed ignition coil on cylinder 1
A clogged or dead fuel injector
Low compression from a valve or piston-ring problem
These are ordered roughly by how often they turn out to be the cause — but the code names a system, not a part. Confirming which one is yours takes data from the running engine.
What does it cost to fix P0301?
$100 – $1,200
Typical US independent-shop range, parts and labour included. It is wide on purpose: the cheap end is usually a sensor, a hose or a cap, and the expensive end is the major component the code was reporting on. Which one you need is a diagnosis, not a guess — and dealer rates run higher than these figures.
Do not guess on P0301
This page explains the code. It cannot tell you which cylinder, coil, or injector is yours — and with a misfire, guessing wrong gets expensive fast. Kaiju Mechanic reads what your car is actually reporting, plus live sensor data through any standard ELM327 adapter, and interprets it against your exact year, make, model and mileage. You can also just ask it about P0301 in chat — no adapter needed for that.
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