What does P0301 mean?

P0301 is “Cylinder 1 Misfire Detected.” The engine computer counted enough misfire events on cylinder 1 to store a code.

Can I swap the coil to test P0301?

Coil swap can move the misfire to another cylinder on some engines — we do it when the design allows and it speeds diagnosis without guessing.

P0301 Check Engine Code

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The problem

P0301 means the computer detected repeated misfires on cylinder 1 specifically. Unlike P0300 (random/multiple), P0301 points to one cylinder — usually ignition (plug, coil, boot) or injector on that hole. A flashing light with P0301 still risks catalytic converter damage from unburned fuel.

Symptoms

Check engine light — may flash under load with active misfire
Rough idle or stumble you can feel at low speed
P0301 alone or with P0300
Recent tune-up where cylinder 1 plug or coil was disturbed
Fuel trim normal or lean on bank including cylinder 1

Can I keep driving with a P0301 code?

Steady light, mild roughness — gentle drive to diagnosis soon.

Flashing light — reduce load immediately; same urgency as P0300.

Do not swap coils randomly without confirming cylinder 1 counts.

Common causes

Failed coil-on-plug or spark plug on cylinder 1
Cracked plug insulator or wrong plug gap
Injector restriction on cylinder 1
Low compression on cylinder 1 (after ignition ruled out)
Vacuum leak affecting cylinder 1 runner on some intakes

What it is often confused with

P0300 random misfire — multiple cylinders or unstable counts
P0302–P0308 — other cylinders; swap test isolates if coil-related

What happens if you ignore it

Catalyst damage from cylinder 1 misfire under load
Coil failure spreading heat to neighboring components
Fouled plug becoming hard to remove

Diagnostic process

1 Confirm misfire counts on cylinder 1 with scan tool
2 Inspect plug and coil; swap coil test when safe and applicable
3 Injector and compression tests when ignition is good

What happens next at LugsNPlugs Automotive?

1 Tell us if the light flashes and whether roughness is constant or only when cold.
2 We isolate cylinder 1 on data before quoting plugs, coils, or deeper work.

Common questions

What does P0301 mean?: P0301 is “Cylinder 1 Misfire Detected.” The engine computer counted enough misfire events on cylinder 1 to store a code.
Can I swap the coil to test P0301?: Coil swap can move the misfire to another cylinder on some engines — we do it when the design allows and it speeds diagnosis without guessing.

Need help with P0301 Check Engine Code?

That's okay — tell us what's going on and a service advisor at LugsNPlugs Automotive will follow up.

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