P0304 on RAM
Cylinder 4 Misfire Detected
P0304 on RAM vehicles indicates cylinder 4 misfire detected. Au7o has documented this code across 3 RAM models — most commonly on 1500, 1500 Classic, 3500. 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 RAM range from $200 to $5,500, 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 RAM by Model
RAM 1500(1 issue)
- HEMI Lifter/Camshaft Failure2009-2019
The 5.7L HEMI engine with Multi-Displacement System (MDS) can experience premature lifter and camshaft wear. The MDS deactivation lifters are prone to failure, causing ticking, misfires, and in severe cases, camshaft lobe damage. This issue has led to class action lawsuits.
RAM 1500 Classic(2 issues)
- 5.7L HEMI MDS Lifter Failure2019-2024
The 5.7L HEMI with Multi-Displacement System (MDS) in the 1500 Classic develops lifter failure, particularly on cylinders that deactivate. The roller lifters can collapse or seize, causing ticking noise and misfires. This is the same issue as the standard 1500.
- MDS Lifter Failure and Hemi Tick (5.7L)2019-2025
The 5.7L Hemi V8 uses Multi-Displacement System (MDS) hydraulic lifters to deactivate four cylinders during light-load cruising. The MDS lifters are known to fail, causing a persistent ticking noise (the infamous "Hemi tick") and misfires on the deactivated cylinders. When an MDS lifter collapses or sticks, it cannot properly deactivate and reactivate the valve, leading to a dead cylinder. In severe cases, a failed lifter can damage the camshaft lobe, requiring a complete top-end rebuild.
RAM 3500(1 issue)
- 6.7L Cummins Exhaust Brake Actuator and VGT Turbo Issues2013-2025
The RAM 3500 6.7L Cummins equipped with the integrated exhaust brake system experiences failures of the VGT (Variable Geometry Turbocharger) actuator and exhaust brake solenoid. The exhaust brake uses the VGT turbo vanes to create backpressure for engine braking while towing. The electronic actuator (Holset HE351VE/HE300VG) sticks or fails due to carbon buildup, causing loss of exhaust brake function, reduced turbo performance, limp mode, and DTC codes P2263 or P006A. TSB 14-001-21 addresses VGT actuator calibration. Actuator replacement costs $800-1,500; complete turbo replacement is $2,500-4,000.
Looking for P0304 on a different make?
View P0304 across all makes →Frequently Asked Questions
What does P0304 mean on RAM?▼
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 RAM specifically, this code is documented across 3 models.
What causes P0304 on RAM vehicles?▼
Common causes on RAM: 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 RAM?▼
Repair costs on RAM range from $200 to $5,500, depending on the specific model and root cause.
Which RAM models have P0304 documented?▼
Au7o has documented P0304 on 3 RAM models: 1500, 1500 Classic, 3500.