P0304 on Volkswagen
Cylinder 4 Misfire Detected
P0304 on Volkswagen vehicles indicates cylinder 4 misfire detected. Au7o has documented this code across 8 Volkswagen models — most commonly on Cabrio, Golf, Golf R. 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 Volkswagen range from $80 to $1,200, 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 Volkswagen by Model
Volkswagen Cabrio(1 issue)
- 2.0L Ignition Coil Pack Failure1999-2002
The 2.0L ABA/AEG engine uses ignition coils that fail prematurely, causing misfires. Same issue as other VW 2.0L vehicles of the era.
Volkswagen Golf(1 issue)
- Direct Injection Carbon Buildup on Intake Valves2008-2021
All EA888 direct-injection 2.0T engines suffer from carbon buildup on the intake valves because fuel is injected directly into the combustion chamber rather than sprayed over the valves. Without fuel washing, oil vapors from the PCV system bake onto the intake valves, reducing airflow and causing drivability issues. Buildup becomes noticeable around 40,000-60,000 miles. VW addressed this in the Gen3 EA888 (2015+) by adding port injection, but the problem persists to some degree in all direct-injection variants.
Volkswagen Golf R(1 issue)
- EA888 Gen 3 Intake Valve Carbon Buildup (GDI)2015-2026
The direct-injected EA888 Gen 3 engine in the Golf R accumulates heavy carbon deposits on the intake valve faces, just like all GDI engines. Since fuel is sprayed directly into the combustion chamber rather than over the intake valves, no fuel-washing occurs to clean the valves. Carbon buildup restricts airflow, causes misfires, rough idle, and measurable power loss. The Golf R's higher boost pressure can partially mask the symptoms, but a carbon-loaded Golf R can lose 15-20 HP from flow restriction.
Volkswagen GTI(1 issue)
- Direct Injection Carbon Buildup on Intake Valves2006-2014
The FSI and TSI direct-injection engines accumulate heavy carbon deposits on the intake valves since fuel is injected directly into the cylinder rather than washing over the valves. This causes misfires, rough idle, and power loss, typically noticeable after 40,000-60,000 miles.
Volkswagen Jetta(2 issues)
- Intake Valve Carbon Buildup2008-2021
Direct injection engines like the 2.0T TSI don't have fuel washing over the intake valves, leading to carbon buildup over time. This restricts airflow and causes performance issues. Typically becomes noticeable after 60,000-80,000 miles.
- Ignition Coil Failure2008-2021
The ignition coils on 2.0T engines can fail, causing misfires, rough running, and check engine lights. This is especially common on older coils and when using aftermarket spark plugs. High boost applications accelerate coil wear.
Volkswagen New Beetle(1 issue)
- Ignition Coil Pack Failure (1.8T/2.0)1998-2011
The individual ignition coil packs on the 1.8T and 2.0L engines fail frequently, causing misfires. This is one of the most common VW repairs of the era. Coils typically fail one at a time.
Volkswagen Rabbit(2 issues)
- 2.5L 5-Cylinder Ignition Coil Pack Failure2006-2009
The 2006-2009 Rabbit with the 2.5L 5-cylinder engine (07K) is notorious for premature ignition coil pack failures. The individual coil-on-plug packs crack internally from heat cycling, causing misfires and rough running. The 5-cylinder layout requires all 5 coils to function properly for smooth operation, and a single failed coil creates noticeable vibration. Coils typically fail between 40,000-80,000 miles.
- Ignition Coil Pack Cracking and Misfires2006-2009
The ignition coil packs on the 2.5L 5-cylinder crack and fail, causing misfires, rough running, and check engine light. The coils often fail one at a time. A well-known weak point of the 2.5L engine.
Volkswagen Taos(1 issue)
- EA211 1.5T Engine Ticking and Fuel Injector Noise2022-2025
The EA211 EVO 1.5T engine in the Taos produces a noticeable ticking/tapping noise that concerns many owners. While some of the noise is normal direct-injection fuel injector operation, excessive ticking can indicate a high-pressure fuel pump issue or hydraulic lifter wear. VW states that direct-injection engines are inherently noisier, but some units produce excessive noise beyond the norm. TSB 20-22-01 addresses abnormal engine noise diagnosis.
Looking for P0304 on a different make?
View P0304 across all makes →Frequently Asked Questions
What does P0304 mean on Volkswagen?▼
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 Volkswagen specifically, this code is documented across 8 models.
What causes P0304 on Volkswagen vehicles?▼
Common causes on Volkswagen: 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 Volkswagen?▼
Repair costs on Volkswagen range from $80 to $1,200, depending on the specific model and root cause.
Which Volkswagen models have P0304 documented?▼
Au7o has documented P0304 on 8 Volkswagen models: Cabrio, Golf, Golf R, GTI, Jetta, New Beetle, Rabbit, Taos.