P0300
High SeverityRandom/Multiple Cylinder Misfire Detected
Ignition System
P0300 — Instant Answer
Random/Multiple Cylinder Misfire Detected
Severity: HIGH SEVERITY
Meaning: 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.
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. Worn spark plugs (35-45% of cases)
- 2. Bad ignition coils (10-25% of cases)
- 3. Vacuum leak affecting multiple cylinders (10-25% of cases)
- 4. Low fuel pressure (10-25% of cases)
Symptoms
- ⚠️Rough idle
- ⚠️Flashing check engine light
- ⚠️Loss of power
- ⚠️Engine shaking or vibration
Related Symptoms
Common Causes
How to Diagnose P0300
- 1Check spark plugs — replace if worn or fouled
- 2Inspect ignition coils for cracks
- 3Check for vacuum leaks
- 4Test fuel pressure
OEM Procedures for P0300
Random/Multiple Cylinder Misfire Detected Found 34 OEM service manual procedures.
Ignition Coil
Ignition Coil & ICM Replacement (HVS) - Installation
Ignition Coil & ICM Replacement (HVS) - Installation
Ignition Coil & ICM Replacement (HVS) - Installation
Ignition Coil & ICM Replacement (HVS) - Installation
Ignition Coil & ICM Replacement (HVS) - Installation
Ignition Coil & ICM Replacement (HVS) - Installation
Ignition Coil & ICM Replacement (HVS) - Installation
Showing 8 of 34 procedures
OEM Diagnostic Flowchart
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Related Resources
Repair guides, symptom pages, and wiring diagrams related to P0300.
Exact Repair Workflows
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Open the exact repair flow most commonly associated with P0300 on this vehicle.
Open the exact repair flow most commonly associated with P0300 on this vehicle.
Open the exact repair flow most commonly associated with P0300 on this vehicle.
Open the exact repair flow most commonly associated with P0300 on this vehicle.
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.
Exact Vehicle Hubs
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Open the exact vehicle hub for a repair workflow commonly associated with P0300.
Open the exact vehicle hub for a repair workflow commonly associated with P0300.
Open the exact vehicle hub for a repair workflow commonly associated with P0300.
Open the exact vehicle hub for a repair workflow commonly associated with P0300.
Open the exact vehicle hub for a repair workflow commonly associated with P0300.
Related Codes
Cylinder 1 is misfiring — not firing properly. Could be spark plug, coil, injector, or compression issue on that specific cylinder.
Cylinder 2 is misfiring.
The engine is running lean on bank 1 — too much air or not enough fuel. The ECM has maxed out its fuel trim trying to compensate. Common causes include vacuum leaks and dirty MAF sensors.
Frequently Asked Questions
- Is P0300 serious?
- Yes — a flashing check engine light means active misfires that can damage the catalytic converter. Pull over if the light flashes.
- Can bad gas cause P0300?
- Yes — contaminated or low-octane fuel can cause random misfires. Try running a tank of premium fuel with fuel system cleaner.
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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