P0301
High SeverityCylinder 1 Misfire Detected
Ignition System
P0301 — Instant Answer
Cylinder 1 Misfire Detected
Severity: HIGH SEVERITY
Meaning: Cylinder 1 is misfiring — not firing properly. Could be spark plug, coil, injector, or compression issue on that specific cylinder.
Safe to drive? NO if CEL is flashing. YES with caution if solid, but repair this week.
Estimated repair cost: $20 - $500
Most common causes:
- 1. Bad spark plug on cylinder 1 (35-45% of cases)
- 2. Faulty ignition coil on cylinder 1 (35-45% of cases)
- 3. Bad fuel injector (10-25% of cases)
- 4. Low compression (valve or gasket) (10-25% of cases)
Symptoms
- ⚠️Rough idle
- ⚠️Loss of power
- ⚠️Check engine light (may flash)
- ⚠️Vibration
Related Symptoms
Common Causes
How to Diagnose P0301
- 1Swap spark plug with known good cylinder — see if misfire moves
- 2Swap coil with another cylinder — see if code follows
- 3Check injector operation
- 4Run compression test if spark and fuel are good
OEM Procedures for P0301
P0301 affects the Spark Plug. Found 116 OEM service manual procedures.
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
1969-73 PEUGEOT 504 4 Cylinder - Spark Plug Tube Replacement
Showing 8 of 116 procedures
OEM Diagnostic Flowchart
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Related Resources
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OEM Manual Evidence
Browse →Mil Comes On With DTCS P0300 Thru P0306 (13-024) — 2013 Acura MDX 3.7L Eng VIN 2 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowl...
Mil Comes On With DTCS P0300 Thru P0306 (13-024) — 2013 Acura MDX 3.7L Eng VIN 2 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowl...
Mil Comes On With DTCS P0300 Thru P0306 (13-024) — 2013 Acura MDX 3.7L Eng VIN 2 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowl...
PGM-FI DTCS — 2013 Acura MDX 3.7L Eng VIN 2 Service Manual ~ LEMON Manuals LEMON Manuals: Repair Knowledge Reimagined Home >> Acura >> 2013...
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Related Symptoms
Browse →Rough idle often traces back to ignition, air metering, vacuum leaks, or timing-related faults before it becomes a full misfire complaint.
A check-engine light is a graph entry point into code pages, symptom-specific diagnosis, and the exact repair categories most often associated with those failures.
Steering wheel shake, brake pedal pulsation, or front-end vibration under braking usually points to rotor, pad, or suspension-related brake issues.
Exact Vehicle Hubs
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Open the exact vehicle hub for a repair workflow commonly associated with P0301.
Open the exact vehicle hub for a repair workflow commonly associated with P0301.
Related Codes
The engine is misfiring across multiple cylinders. This is often caused by something that affects all cylinders — spark plugs, fuel quality, vacuum leak, or low compression.
Cylinder 2 is misfiring.
The fuel injector on cylinder 1 has a circuit fault. It may not be firing.
Frequently Asked Questions
- How do I find cylinder 1?
- Cylinder 1 location varies by engine. Check your repair manual. On most inline engines, it is at the front (belt end).
- Can I just replace one spark plug?
- You can, but it is recommended to replace all plugs at the same time since they wear together.
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Author & Review
Written by AllOEMManuals Editorial Team. Reviewed by ASE-certified technicians and updated with factory-reference checks for fitment-sensitive steps.
This guide was drafted with AI assistance and reviewed for accuracy by a human editor.
Last updated: 2026-05-07