P0300 on a 2022 Ram 1500 Classic Crew Cab
P0300 is a generic OBD2 powertrain code for random or multiple cylinder misfire. Unlike P0301 through P0308, it does not point to one specific cylinder, so the cause can be ignition, fuel, air, sensor, or mechanical.
Not your vehicle? See general P0300 info.
Most common causes on the 2022 Ram 1500 Classic Crew Cab
Ranked from 588 NHTSA owner complaints filed for this vehicle.
- 1
Intake manifold swirl valve (ISV/actuator) failure
High severityAn owner identifies a failed 'OEM Actuator Manifold Runner'/swirl valve actuator on the 5.7L HEMI intake -- a well-known cause of rough running/misfire on this engine family when the actuator or its linkage fails.
Reported in 1 NHTSA complaint - 2
Collapsed MDS lifter / cam lobe wear from oil starvation
High severityOne owner's dealer replaced the camshaft and oil pan pickup for an MDS lifter/cam oiling problem described as a long-running issue on this engine family; a collapsed lifter drops valve lift on that cylinder and produces a persistent misfire.
Reported in 1 NHTSA complaint - 3
Failing fuel injector
Medium severityA dealer diagnosed fuel injector failure after the Check Engine light illuminated and the engine lost power/became inoperable.
Reported in 1 NHTSA complaintParts:fuel injector - 4
Worn spark plugs
Low severityWorn or fouled plugs are the most common misfire cause; inspect gap and condition, especially on long change intervals.
Common causeParts:spark plug - 5
Failing ignition coil
Medium severityA weak or intermittently-arcing coil produces a repeatable misfire on the affected cylinder, often worse under load or heat.
Common causeParts:ignition coil - 6
Vacuum leak
Low severityUnmetered air entering through a cracked hose or gasket leans out one or more cylinders enough to misfire.
Common cause - 7
Carbon-fouled intake valves
Low severityCarbon buildup on the intake valve backs disrupts airflow/atomization enough to cause a misfire, especially on engines that see frequent MDS cylinder deactivation.
Common cause - 8
Low compression from worn rings or valves
Medium severityReduced cylinder sealing (worn rings, burnt valve) makes that cylinder unable to combust reliably, producing a chronic misfire.
Common cause - 9
EGR valve fault
Low severityA stuck-open EGR valve over-dilutes the intake charge at idle/low load, causing a rough-running misfire.
Common causeParts:EGR valve
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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0300 on your car still needs shop confirmation before any repair.
Common symptoms
- Flashing or steady check engine light
- Rough idle
- Shaking under acceleration
- Loss of power
- Fuel smell from exhaust
What to check before replacing parts
Scan for cylinder-specific misfire codes
Look for: A companion P0301–P0308 pins the misfire to one cylinder — start there. P0300 with no cylinder code points at something hitting several at once: fuel pressure, a large vacuum leak, or timing.
Inspect the spark plugs and coils
Look for: Pull the plugs: black/sooty = rich, oily = oil intrusion, white/blistered = lean or overheating, cracked porcelain or an out-of-spec gap = replace. Then swap a coil to another cylinder — if a cylinder-specific code follows the coil, the coil is bad.
Check fuel trims for a vacuum leak
Look for: High positive short- and long-term trims (worst at idle, improving as RPM rises) mean unmetered air is getting in. Smoke-test the intake and listen for hissing.
Verify fuel pressure
Look for: Compare running/cranking pressure to the vehicle spec. Low or dropping pressure starves multiple cylinders and reads as a random misfire — suspect the pump, filter, or regulator.
Compression / leak-down test if ignition and fuel check out
Look for: A cylinder 15%+ below the others, or leak-down hissing from the intake (intake valve), exhaust (exhaust valve), or oil filler (rings), means the misfire is mechanical — not a swap-in part.
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