P0308
High SeverityCylinder 8 Misfire Detected
Ignition System
What Does P0308 Mean?
Cylinder 8 is misfiring. Only on V8 engines.
Common Fix
Replace spark plug or coil
Estimated Cost (DIY)
$20 - $500
Common Causes
How to Diagnose P0308
- 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 P0308.
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 P0308 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 grounded by OEM manual evidence related to P0308.
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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 7 is misfiring. Only on V8 engines.
Frequently Asked Questions
- How many spark plugs does a V8 need?
- Standard V8: 8 plugs. HEMI with dual spark: 16 plugs.
- Is a V8 tune-up expensive?
- DIY: $40-$120 for plugs. If adding coils, $200-$400. HEMI 16-plug engines are on the higher end.
Related Repair Guides
If your vehicle has triggered P0308, these DIY repair guides may help: