P0300 on RAM
Random/Multiple Cylinder Misfire Detected
P0300 on RAM vehicles indicates random/multiple cylinder misfire detected. Au7o has documented this code across 3 RAM models — most commonly on 1500, 1500 Classic, 3500. P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. Typical repair costs on RAM range from $200 to $7,000, depending on the specific model and root cause.
Common Causes of P0300
- •Worn or fouled spark plugs (across cylinders)
- •Vacuum or intake air leak
- •Weak fuel pump, clogged fuel filter, or low fuel pressure
- •Failing ignition coils or worn spark plug wires
- •Dirty or faulty mass airflow (MAF) sensor
- •Clogged or dirty fuel injectors
- •Faulty crankshaft/camshaft position sensor
- •Low compression or EGR/PCV system faults
P0300 on RAM by Model
RAM 1500(2 issues)
- 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.
- 5.7L HEMI MDS lifter collapse and camshaft lobe wear ("HEMI tick" leading to engine damage)2014-2023
The 5.7L HEMI (Gen III) with the Multi-Displacement System (MDS) is well documented for roller-lifter failure that progresses into camshaft lobe damage. The MDS deactivation lifters and the engine's circuitous oiling path (oil routed through the deck, head gasket, and rocker shaft to the lifter bore) leave lifter bores oil-starved at low RPM. Improperly hardened lifter roller/needle assemblies allow needles to breach the surface hardening, spalling the roller and then wiping the cam lobe. It starts as a rhythmic cold-start/idle tick and can end in metal debris throughout the engine and total failure, sometimes at very low mileage. This is the subject of the Petro et al. v. FCA US LLC class action (D. Del., No. 1:22-cv-00621) covering 2014+ 5.7L and 6.4L HEMI engines. FCA revised the lifter design around 2018 (larger needles) but failures continued to be reported afterward.
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.
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View P0300 across all makes →Frequently Asked Questions
What does P0300 mean on RAM?▼
P0300 stands for "Random/Multiple Cylinder Misfire Detected." P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. On RAM specifically, this code is documented across 3 models.
What causes P0300 on RAM vehicles?▼
Common causes on RAM: Worn or fouled spark plugs (across cylinders), Vacuum or intake air leak, Weak fuel pump, clogged fuel filter, or low fuel pressure, Failing ignition coils or worn spark plug wires, Dirty or faulty mass airflow (MAF) sensor. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0300 on a RAM?▼
Repair costs on RAM range from $200 to $7,000, depending on the specific model and root cause.
Which RAM models have P0300 documented?▼
Au7o has documented P0300 on 3 RAM models: 1500, 1500 Classic, 3500.