P0308 on Chevrolet
Cylinder 8 Misfire Detected
P0308 on Chevrolet vehicles indicates cylinder 8 misfire detected. Au7o has documented this code across 2 Chevrolet models — most commonly on Silverado 2500HD, Suburban. P0308 means the engine computer detected a misfire on cylinder number 8 — that cylinder is failing to combust properly or at the correct time. The PCM identifies it by monitoring crankshaft speed variations as cylinder 8 fires. Misfires waste fuel, increase emissions, and can overheat and damage the catalytic converter, so a hard misfire may cause a flashing check engine light. Typical symptoms include rough idle, vibration, hesitation, and reduced power. Typical repair costs on Chevrolet range from $100 to $4,000, depending on the specific model and root cause.
Common Causes of P0308
- •Worn, fouled, or incorrectly gapped spark plug on cylinder 8
- •Failed ignition coil or coil-on-plug for cylinder 8
- •Faulty, clogged, or leaking fuel injector
- •Vacuum or intake air leak affecting that cylinder
- •Low compression (worn rings, burnt/leaking valve, head gasket)
- •Damaged spark plug wire or boot (on applicable engines)
- •Carbon buildup or sticking valve
P0308 on Chevrolet by Model
Chevrolet Silverado 2500HD(1 issue)
- Injector Wiring Harness Chafing (Duramax)2001-2016
The fuel injector wiring harness on the Duramax diesel routes across the top of the engine under the valve covers. The harness rubs against the valve cover and rocker arms, causing the insulation to wear through and the wires to short or open. When an injector wire is damaged, the affected cylinder misfires, the engine runs rough, and white smoke pours from the exhaust. The chafing is accelerated by engine vibration and can affect multiple cylinders over time. GM released updated harness routing clips but the fundamental design has the harness in a high-wear location.
Chevrolet Suburban(1 issue)
- AFM/DFM Lifter Failure (5.3L/6.2L V8)2007-2025
The Active Fuel Management (AFM) and Dynamic Fuel Management (DFM) systems on the 5.3L and 6.2L V8 engines deactivate cylinders to save fuel by collapsing hydraulic valve lifters. These lifters have a complex locking pin mechanism that fails, causing the lifter to collapse and the affected cylinder to misfire. A collapsed lifter can also damage the camshaft lobe it rides on, turning a $300 lifter into a $3,000 camshaft and lifter replacement. The issue affects 2007+ Suburbans and is one of the most complained-about GM V8 problems. GM switched from 4-cylinder AFM to 17-pattern DFM in 2019, but lifter failures continue.
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View P0308 across all makes →Frequently Asked Questions
What does P0308 mean on Chevrolet?▼
P0308 stands for "Cylinder 8 Misfire Detected." P0308 means the engine computer detected a misfire on cylinder number 8 — that cylinder is failing to combust properly or at the correct time. The PCM identifies it by monitoring crankshaft speed variations as cylinder 8 fires. Misfires waste fuel, increase emissions, and can overheat and damage the catalytic converter, so a hard misfire may cause a flashing check engine light. Typical symptoms include rough idle, vibration, hesitation, and reduced power. On Chevrolet specifically, this code is documented across 2 models.
What causes P0308 on Chevrolet vehicles?▼
Common causes on Chevrolet: Worn, fouled, or incorrectly gapped spark plug on cylinder 8, Failed ignition coil or coil-on-plug for cylinder 8, Faulty, clogged, or leaking fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/leaking valve, head gasket). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0308 on a Chevrolet?▼
Repair costs on Chevrolet range from $100 to $4,000, depending on the specific model and root cause.
Which Chevrolet models have P0308 documented?▼
Au7o has documented P0308 on 2 Chevrolet models: Silverado 2500HD, Suburban.