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P0300

P0300 on a 2021 Ford F 150 Super Crew

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 2021 Ford F 150 Super Crew

Ranked from 941 NHTSA owner complaints filed for this vehicle.

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  1. 1

    Excessive oil consumption leading to fouled plugs/low oil

    High severity

    Four complaints describe the 5.0L Coyote V8 in this truck burning oil down to critically low levels; oil-fouled plugs and marginal lubrication can both contribute to rough running and misfire.

    Reported in 4 NHTSA complaints
  2. 2

    Cracked or failing spark plugs

    Medium severity

    Two complaints on this truck report misfire traced to spark plugs -- one to two cracked plugs at 51k miles, another where all six plugs were replaced under an active misfire recall (NHTSA 2025-366).

    Reported in 2 NHTSA complaints
    Parts:spark plug
  3. 3

    Failing ignition coil(s)

    Medium severity

    Two complaints describe ignition coils being replaced (one, then a full set) as part of chasing a persistent misfire on this truck.

    Reported in 2 NHTSA complaints
    Parts:ignition coil
  4. 4

    Cracked or leaking high-pressure fuel injector

    High severity

    Two complaints document a cracked high-pressure injector spraying fuel and causing cylinder misfire/fuel loss, in one case severe enough to be a fire risk; injectors were among parts replaced while chasing misfire on another truck.

    Reported in 2 NHTSA complaints
    Parts:fuel injector
  5. 5

    Low compression from valve or piston damage

    High severity

    One complaint documents a confirmed compression loss on cylinder #4 with visible piston-top damage attributed to valve failure, producing a persistent misfire.

    Reported in 1 NHTSA complaint
  6. 6

    Timing chain / cam phaser fault

    High severity

    One complaint reports an abnormal rattle with the Ford app flagging a timing failure, a known driver of misfire when chain stretch or phaser wear throws valve timing off.

    Reported in 1 NHTSA complaint
    Parts:timing chaincam phaser
  7. 7

    Vacuum or intake leak

    Medium severity

    Unmetered air entering downstream of the throttle body leans out a cylinder enough to misfire; smoke-test the intake to confirm.

    Common cause
  8. 8

    Carbon-fouled intake valves

    Low severity

    Direct-injected V8s accumulate carbon on the intake valves over time, disrupting airflow/fuel atomization enough to cause a misfire; a borescope check confirms.

    Common cause

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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

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