P0304 on Genesis
Cylinder 4 Misfire Detected
P0304 on Genesis vehicles indicates cylinder 4 misfire detected. Au7o has documented this code across 1 Genesis model — most commonly on GV80. 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.
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 Genesis by Model
Genesis GV80(1 issue)
- 2.5L T-GDI Cold-Start Misfire P0300-P0304 (Service Campaign 914G / TSB 25-01-051G)2021-2024
Theta III 2.5L T-GDI engines in GV80 JX1 (and related G80/GV70) illuminate the Check Engine light with random or specific cylinder misfire codes P0300-P0304 during cold start. Root cause is identified as ECM misfire-detection logic; Genesis issued service campaign 914G covering 2021-2024MY GV80 built 07/27/2020-03/04/2024 for a free ECM reflash.
Looking for P0304 on a different make?
View P0304 across all makes →Frequently Asked Questions
What does P0304 mean on Genesis?▼
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 Genesis specifically, this code is documented across 1 model.
What causes P0304 on Genesis vehicles?▼
Common causes on Genesis: 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 Genesis?▼
Repair costs vary widely depending on the root cause and specific Genesis model.
Which Genesis models have P0304 documented?▼
Au7o has documented P0304 on 1 Genesis model: GV80.