P0305 on Chevrolet
Cylinder 5 Misfire Detected
P0305 on Chevrolet vehicles indicates cylinder 5 misfire detected. Au7o has documented this code across 3 Chevrolet models — most commonly on Colorado, Silverado 2500HD, Suburban. This code means the engine control module detected a misfire on cylinder number 5, meaning that cylinder is not burning its air-fuel mixture properly on some combustion cycles. The computer senses misfires by watching for tiny fluctuations in crankshaft speed each time a cylinder fails to fire correctly. A misfire wastes fuel, can make the engine run rough or shake, and dumps unburned fuel into the exhaust, which can overheat and damage the catalytic converter. It generally points to a problem with spark, fuel delivery, or compression specifically affecting cylinder 5. Typical repair costs on Chevrolet range from $100 to $4,000, depending on the specific model and root cause.
Common Causes of P0305
- •Worn or fouled spark plug on cylinder 5
- •Failed ignition coil or coil pack for cylinder 5
- •Faulty or clogged fuel injector on cylinder 5
- •Vacuum or intake air leak affecting that cylinder
- •Bad spark plug wire or boot (on applicable engines)
- •Low compression from worn rings, valves, or head gasket
- •Carbon buildup or sticking valve on cylinder 5
- •Lean or rich fuel condition affecting the cylinder
P0305 on Chevrolet by Model
Chevrolet Colorado(1 issue)
- Cylinder Head Valve Seat Failure and Misfire on 3.5L/3.7L Inline-Five2004-2012
A well-documented problem on the Atlas inline-five engines is dropped or loosened valve seats in the cylinder head, often after overheating or repeated thermal cycling. Owners report sudden misfires, rough running, low compression, flashing MIL, and in some cases complete loss of power. This issue appears in owner forums, repair discussions, and NHTSA complaints, and typically requires cylinder head replacement or machine work rather than simple ignition parts.
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 P0305 across all makes →Frequently Asked Questions
What does P0305 mean on Chevrolet?▼
P0305 stands for "Cylinder 5 Misfire Detected." This code means the engine control module detected a misfire on cylinder number 5, meaning that cylinder is not burning its air-fuel mixture properly on some combustion cycles. The computer senses misfires by watching for tiny fluctuations in crankshaft speed each time a cylinder fails to fire correctly. A misfire wastes fuel, can make the engine run rough or shake, and dumps unburned fuel into the exhaust, which can overheat and damage the catalytic converter. It generally points to a problem with spark, fuel delivery, or compression specifically affecting cylinder 5. On Chevrolet specifically, this code is documented across 3 models.
What causes P0305 on Chevrolet vehicles?▼
Common causes on Chevrolet: Worn or fouled spark plug on cylinder 5, Failed ignition coil or coil pack for cylinder 5, Faulty or clogged fuel injector on cylinder 5, Vacuum or intake air leak affecting that cylinder, Bad spark plug wire or boot (on applicable engines). Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0305 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 P0305 documented?▼
Au7o has documented P0305 on 3 Chevrolet models: Colorado, Silverado 2500HD, Suburban.