P0300 on a 2019 Ford F 350 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 2019 Ford F 350 Crew

Ranked from 463 NHTSA owner complaints filed for this vehicle.

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1
Fuel supply line or filter housing failure causing fuel starvation
High severity
Owners reported the fuel line/filter clip failing and blowing off, and a separate fuel-system-leak code, either of which can starve cylinders of fuel and cause rough running/misfire.
Reported in 2 NHTSA complaints
Parts:fuel line fuel filter
2
CP4 high-pressure fuel pump failure contaminating injectors
High severity
A reported CP4 pump failure sent metal shavings through the fuel injectors, requiring a full fuel-system rebuild — a known catastrophic failure mode on the 6.7L Powerstroke.
Reported in 1 NHTSA complaint
Parts:fuel pump fuel injector
3
Turbocharger failure causing rough running under load
Medium severity
A clanking noise diagnosed as a failed turbocharger can disrupt the air/fuel mix under boost, contributing to misfire-like symptoms.
Reported in 1 NHTSA complaint
Parts:turbocharger
4
Clogged or worn fuel injectors
Medium severity
Diesel injectors that are worn or partially clogged deliver an uneven spray pattern, producing a rough idle or misfire on one or more cylinders.
Common cause
Parts:fuel injector
5
Glow plug failure
Medium severity
A failed glow plug causes a cold-start or cold-weather misfire on the affected cylinder; check glow plug resistance/current draw.
Common cause
Parts:glow plug
6
Low compression from worn rings or valves
High severity
Mechanical wear reduces cylinder sealing and combustion efficiency, producing a misfire that won't clear with electrical/fuel repairs; confirm with a compression or leak-down test.
Common cause
7
EGR valve fault causing rough idle
Medium severity
A stuck or leaking EGR valve can upset the air/fuel charge at idle and low load, producing a misfire-like stumble.
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

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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Matching symptoms

Car Runs Rough Flashing Check Engine Light