P0304 on Porsche
Cylinder 4 Misfire Detected
P0304 on Porsche vehicles indicates cylinder 4 misfire detected. Au7o has documented this code across 1 Porsche model — most commonly on Panamera. This code means the engine computer detected a misfire in cylinder number 4 — that cylinder isn't igniting its air-fuel mixture fully or at all. The system detects this by monitoring small changes in crankshaft rotation speed as each cylinder fires. You may feel a rough idle, shaking, hesitation or reduced power, and a persistent misfire can dump unburned fuel into the exhaust and overheat or damage the catalytic converter. Since it's pinpointed to one cylinder, the problem typically lies in that cylinder's spark, fuel, or compression. Typical repair costs on Porsche range from $600 to $1,600, depending on the specific model and root cause.
Common Causes of P0304
- •Worn or fouled spark plug in cylinder 4
- •Failed or weak ignition coil on cylinder 4
- •Faulty spark plug wire or boot (where applicable)
- •Clogged, stuck or leaking fuel injector for cylinder 4
- •Vacuum or intake air leak near that cylinder
- •Low compression (worn rings, burnt/leaking valve, head gasket)
- •Damaged wiring or connector at the coil or injector
P0304 on Porsche by Model
Porsche Panamera(1 issue)
- Direct-Injection Intake Valve Carbon Buildup and Misfire2010-2024
Every Panamera engine uses direct fuel injection, so no fuel ever washes across the back of the intake valves. Oil vapour drawn in through the PCV system bakes onto the valve stems and ports and gradually chokes airflow. On the naturally aspirated 3.6 V6 fitted to the base 970 the deposits are the classic case, and the boosted V6s show the same pattern. Symptoms are progressive rather than sudden: rough or lopey idle first, then hesitation and dulled throttle response, then stored misfire codes as the deposits become severe enough to disturb cylinder filling. Owners typically notice it somewhere between roughly 50,000 and 80,000 miles. This is an architectural characteristic of DFI, not a manufacturing defect, and no recall or warranty extension covers it - which is exactly why it catches second and third owners out.
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View P0304 across all makes →Frequently Asked Questions
What does P0304 mean on Porsche?▼
P0304 stands for "Cylinder 4 Misfire Detected." This code means the engine computer detected a misfire in cylinder number 4 — that cylinder isn't igniting its air-fuel mixture fully or at all. The system detects this by monitoring small changes in crankshaft rotation speed as each cylinder fires. You may feel a rough idle, shaking, hesitation or reduced power, and a persistent misfire can dump unburned fuel into the exhaust and overheat or damage the catalytic converter. Since it's pinpointed to one cylinder, the problem typically lies in that cylinder's spark, fuel, or compression. On Porsche specifically, this code is documented across 1 model.
What causes P0304 on Porsche vehicles?▼
Common causes on Porsche: Worn or fouled spark plug in cylinder 4, Failed or weak ignition coil on cylinder 4, Faulty spark plug wire or boot (where applicable), Clogged, stuck or leaking fuel injector for cylinder 4, Vacuum or intake air leak near that cylinder. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0304 on a Porsche?▼
Repair costs on Porsche range from $600 to $1,600, depending on the specific model and root cause.
Which Porsche models have P0304 documented?▼
Au7o has documented P0304 on 1 Porsche model: Panamera.