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P0300

P0300 on a 2017 Ford F 250 Supercab

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 2017 Ford F 250 Supercab

Ranked from 1,155 NHTSA owner complaints filed for this vehicle.

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  1. 1

    Low fuel rail pressure from high-pressure pump failure causing fuel-starvation misfire

    High severity

    Multiple complaints on this exact vehicle report 'Low Fuel Pressure'/'Reduced Power' warnings, stalling, and a fuel filter full of metal shavings — insufficient fuel delivery to the injectors that manifests as a misfire.

    Reported in 5 NHTSA complaints
  2. 2

    EGR system fault

    Medium severity

    A dealer diagnosed a faulty EGR valve needing replacement on this vehicle after a persistent check-engine light.

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

    Worn or carbon-fouled spark plugs

    Medium severity

    Plugs beyond service interval develop wide gaps or heavy carbon/oil fouling and misfire under load; pull and inspect gap and electrode wear on all cylinders.

    Common cause
  4. 4

    Failing ignition coil(s)

    Medium severity

    A cracked or heat-degraded coil produces a weak or intermittent spark on one cylinder; swapping the coil to a different cylinder and watching the misfire follow it confirms this.

    Common cause
  5. 5

    Clogged or leaking fuel injector(s)

    Medium severity

    A partially clogged or dribbling injector under- or over-fuels a cylinder; an injector balance/flow test isolates the bad one.

    Common cause
  6. 6

    Vacuum or intake air leak

    Medium severity

    Unmetered air entering after the airflow sensor leans one or more cylinders and destabilizes idle; smoke-test the intake tract, PCV, and brake booster hoses.

    Common cause
  7. 7

    Carbon-fouled intake valves

    Low severity

    Direct-injection engines build carbon deposits on the back of the intake valves that disrupt airflow and atomization, especially at idle/low RPM; confirmed with a borescope.

    Common cause
  8. 8

    Low cylinder compression (worn rings/valves)

    High severity

    Mechanical wear that no ignition or fuel part will fix; a compression or leak-down test confirms it and points to internal engine repair.

    Common cause
  9. 9

    EGR system fault

    Medium severity

    A stuck-open EGR valve or passage dumps excess exhaust gas into the intake at idle/cruise and destabilizes combustion.

    Common cause
    Parts: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

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

P0300 on 2017 Ford F 250 Supercab: Causes, Symptoms & Fixes