P0304 on Jaguar
Cylinder 4 Misfire Detected
P0304 on Jaguar vehicles indicates cylinder 4 misfire detected. Au7o has documented this code across 1 Jaguar model — most commonly on XK. 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 Jaguar range from $300 to $1,000, 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 Jaguar by Model
Jaguar XK(1 issue)
- Ignition Coil-on-Plug Misfire (Oil-Fouled Coils)2007-2015
The AJ-V8 uses individual coil-on-plug ignition coils that fail with age and heat, producing single- or multi-cylinder misfires and a check-engine light. A frequent contributor is oil pooling in the spark-plug wells from a leaking cam-cover gasket, which fouls the coil boots. Coils typically last 70k-100k miles but wear faster with heavy idling and heat cycling.
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View P0304 across all makes →Frequently Asked Questions
What does P0304 mean on Jaguar?▼
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 Jaguar specifically, this code is documented across 1 model.
What causes P0304 on Jaguar vehicles?▼
Common causes on Jaguar: 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 Jaguar?▼
Repair costs on Jaguar range from $300 to $1,000, depending on the specific model and root cause.
Which Jaguar models have P0304 documented?▼
Au7o has documented P0304 on 1 Jaguar model: XK.