P0305 on Lexus
Cylinder 5 Misfire Detected
P0305 on Lexus vehicles indicates cylinder 5 misfire detected. Au7o has documented this code across 1 Lexus model — most commonly on IS. 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 Lexus range from $250 to $900, 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 Lexus by Model
Lexus IS(1 issue)
- Valve Cover Gasket Leaks Causing Oil Smell and Misfire Risk2001-2005
Aging valve cover gaskets on the 2JZ-GE commonly harden and leak, allowing oil to seep onto the cylinder head, spark plug tube seals, and exhaust side of the engine. Owners often notice a burnt-oil smell, visible oil around the valve covers, and occasional misfires if oil contaminates ignition components. This is one of the most common age-related engine leaks on the first-gen IS300.
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View P0305 across all makes →Frequently Asked Questions
What does P0305 mean on Lexus?▼
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 Lexus specifically, this code is documented across 1 model.
What causes P0305 on Lexus vehicles?▼
Common causes on Lexus: 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 Lexus?▼
Repair costs on Lexus range from $250 to $900, depending on the specific model and root cause.
Which Lexus models have P0305 documented?▼
Au7o has documented P0305 on 1 Lexus model: IS.