P0304 on Saturn
Cylinder 4 Misfire Detected
P0304 on Saturn vehicles indicates cylinder 4 misfire detected. Au7o has documented this code across 3 Saturn models — most commonly on Aura, S-Series, Vue. 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 Saturn range from $50 to $800, 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 Saturn by Model
Saturn Aura(1 issue)
- 3.6L Random/Multiple-Cylinder Misfire2007-2009
The 3.6L V6 Auras are reported to throw misfire codes, frequently as a downstream symptom of the stretched timing chains but also from worn ignition coils/spark plugs or carbon buildup on the direct-injection intake valves. Owners experience rough idle, hesitation, and a check engine light. P0300 with cylinder-specific misfire codes is common.
Saturn S-Series(1 issue)
- DIS Ignition Module / Coil Pack Failure Causing Cylinder Misfires1991-1999
The Saturn S-Series uses a Distributorless Ignition System (DIS) with a waste-spark coil pack mounted on top of the engine. The coils and the Ignition Control Module (ICM) fail with age, throwing P0300-series misfire codes (commonly P0301 or P0302). A subtle but documented contributor is poor grounding: the ICM grounds to the transmission bellhousing via a stud, and corrosion on this ground path causes intermittent misfires that are easily misdiagnosed as coil failure. The waste-spark design uses the #4 plug firing on the compression stroke to fake a cam signal, so if the #4 coil weakens, the DIS may also lose its cam-position reference, causing cascading driveability issues.
Saturn Vue(1 issue)
- V6 Valve Cover Gasket Oil Leak Soaking Coil Boots → Misfires2004-2007
On the 3.0L and 3.5L V6 Vue models, the valve cover gaskets become brittle and leak oil down into the spark plug tubes. The oil soaks the coil-on-plug boots, causing the rubber to swell and degrade so spark grounds out, producing misfires and rough running. Oil also drips onto the exhaust manifold, creating a burning-oil smell.
Looking for P0304 on a different make?
View P0304 across all makes →Frequently Asked Questions
What does P0304 mean on Saturn?▼
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 Saturn specifically, this code is documented across 3 models.
What causes P0304 on Saturn vehicles?▼
Common causes on Saturn: 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 Saturn?▼
Repair costs on Saturn range from $50 to $800, depending on the specific model and root cause.
Which Saturn models have P0304 documented?▼
Au7o has documented P0304 on 3 Saturn models: Aura, S-Series, Vue.