P0306
High SeverityCylinder 6 Misfire Detected
Ignition System
What Does P0306 Mean?
Cylinder 6 is misfiring. Only on 6+ cylinder engines.
Common Fix
Replace spark plug or coil
Estimated Cost (DIY)
$20 - $500
Common Causes
How to Diagnose P0306
- 1Swap plug/coil
- 2Check injector
- 3Compression test
OEM Diagnostic Flowchart
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Related Resources
Repair guides, symptom pages, and wiring diagrams related to P0306.
OEM Manual Evidence
Browse →A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL Denali AWD V8-6.2L Service Manual | Operation CHARM Operation CHARM : Car...
A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL Denali 2WD V8-6.2L Service Manual | Operation CHARM Operation CHARM : Car...
A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL 4WD V8-6.0L Service Manual | Operation CHARM Operation CHARM : Car repair...
A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL 4WD V8-5.3L Service Manual | Operation CHARM Operation CHARM : Car repair...
Exact Repair Workflows
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Open the exact repair flow most commonly associated with P0306 on this vehicle.
Open the exact repair flow most commonly associated with P0306 on this vehicle.
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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.
Exact Vehicle Hubs
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Open the exact vehicle hub for a repair workflow commonly associated with P0306.
Open the exact vehicle hub for a repair workflow commonly associated with P0306.
Open the exact vehicle hub grounded by OEM manual evidence related to P0306.
Open the exact vehicle hub grounded by OEM manual evidence related to P0306.
Open the exact vehicle hub grounded by OEM manual evidence related to P0306.
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 5 is misfiring. Only on 5+ cylinder engines.
Cylinder 7 is misfiring. Only on V8 engines.
Frequently Asked Questions
- Is cylinder 6 hard to reach?
- On V6 engines, cylinder 6 is usually at the back of bank 2. It can be harder to access than front cylinders.
- Do I need to replace all 6 coils?
- Only if they are all original and high-mileage. Otherwise, just replace the failed one.
Related Repair Guides
If your vehicle has triggered P0306, these DIY repair guides may help: