P0301 - Cylinder 1 Misfire Detected
Plain-English meaning
The engine control module (ECM) has detected a misfire in cylinder number 1.
What to check first
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What not to replace yet
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Stop driving when
If the vehicle experiences severe rough running, stalling, or loss of power that compromises safety, stop driving and seek professional assistance.
Related symptoms
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Owner steps
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Likely causes
Faulty spark plug in cylinder 1 (medium)
Defective ignition coil or ignition wire for cylinder 1 (medium)
Fuel injector malfunction in cylinder 1 (medium)
Vacuum leak near cylinder 1 (medium)
Low fuel pressure or fuel delivery issues (medium)
Compression problems in cylinder 1 (e.g., worn piston rings, valves) (medium)
Faulty engine control module (rare) (medium)
Shop steps
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Follow-up questions
When did you first notice the issue?
Is the Check Engine Light on continuously or flashing?
Have there been any recent repairs or maintenance?
Are there any unusual noises or smells from the engine?
What is the vehicle's make, model, year, and mileage?