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P0300

P0300 on a 2016 Ram 1500

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 2016 Ram 1500

Ranked from 1,508 NHTSA owner complaints filed for this vehicle.

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  1. 1

    Crankshaft position sensor / reluctor ring (tone wheel) failure

    High severity

    Multiple owners describe a crankshaft position fault -- including the 'Loss of Crank Position' NHTSA recall (W68/20V-475) and a failed magnetic tone wheel -- causing sudden stalling and rough running severe enough to set misfire-type codes.

    Reported in 4 NHTSA complaints
    Parts:crankshaft position sensor
  2. 2

    Collapsed valve lifter / worn camshaft lobe (5.7L HEMI)

    High severity

    One owner describes the well-known HEMI lifter-bearing/cam-lobe wear pattern ('eats the cam'), which drops a cylinder's valve event and produces a persistent misfire.

    Reported in 1 NHTSA complaint
    Parts:valve lifterscamshaft
  3. 3

    Intake manifold leak or defect (3.0L EcoDiesel)

    Medium severity

    An owner reports a dealer-confirmed need to replace the intake manifold on the EcoDiesel for hesitation, drag, and a check engine light -- an intake air-path fault that can disrupt smooth combustion.

    Reported in 1 NHTSA complaint
    Parts:intake manifold
  4. 4

    Worn or fouled spark plugs (5.7L HEMI gas engine)

    Medium severity

    Aged or fouled plugs are a top standalone cause of random misfire on the gas HEMI variant of this truck.

    Common cause
    Parts:spark plugs
  5. 5

    Failing ignition coil

    Medium severity

    A weak coil misfires under load and often sets a cylinder-specific code alongside P0300.

    Common cause
    Parts:ignition coil
  6. 6

    Clogged or leaking fuel injector

    Medium severity

    Uneven fuel delivery to a cylinder, whether gas port injector or diesel injector, produces a repeatable misfire on that cylinder.

    Common cause
    Parts:fuel injector
  7. 7

    Vacuum or intake air leak

    Medium severity

    Unmetered air entering after the airflow sensor leans out the mixture enough to cause a misfire, particularly at idle.

    Common cause
  8. 8

    EGR valve stuck open

    Low severity

    An EGR valve that won't fully close dilutes the intake charge with exhaust gas, which can trigger a misfire at idle or light load.

    Common cause
    Parts:EGR valve

Part links go to Amazon search results for this vehicle. As an Amazon Associate, WrenchConnect earns from qualifying purchases — always confirm fitment for your exact trim and engine before ordering.

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

1

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.

2

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.

3

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.

4

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.

5

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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Matching symptoms

Car Runs RoughFlashing Check Engine Light