P0300 on a 2019 Ford F 350 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 2019 Ford F 350 Supercab

Ranked from 463 NHTSA owner complaints filed for this vehicle.

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1
CP4 high-pressure fuel pump failure contaminating injectors with metal debris
High severity
The CP4 pump is documented to internally fail and send metal shavings through the fuel rail into the injectors, causing misfire, stumble, or sudden shutdown; two complaints describe exactly this failure mode on this truck.
Reported in 2 NHTSA complaints
Parts:high-pressure fuel pump fuel injectors fuel filter fuel rail
2
Cracked or leaking upper fuel filter/fuel line assembly causing fuel delivery interruption
High severity
Owners report the fuel line/filter housing on top of the 6.7L cracking or blowing off, spraying diesel and interrupting steady fuel delivery to the injectors, which produces a rough-running/misfire condition.
Reported in 2 NHTSA complaints
Parts:fuel filter housing fuel line
3
Mass airflow (MAF) sensor fault (documented service bulletin on 6.7L engines)
Medium severity
A service bulletin cited by an owner covers known MAF sensor problems on the 6.7L causing limp/regen faults and abrupt shutdowns, which present as misfire-like rough running.
Reported in 1 NHTSA complaint
Parts:mass airflow sensor
4
Turbocharger failure or boost/charge-air leak
High severity
A reported turbocharger and engine failure with abnormal clanking at moderate speed is consistent with a boost leak or turbo failure causing an uneven air/fuel mixture and rough running.
Reported in 1 NHTSA complaint
Parts:turbocharger charge air hose
5
Worn or clogged diesel fuel injectors
Medium severity
Injector spray pattern degrades with age/contamination, producing an uneven cylinder-to-cylinder misfire; a common wear item on high-mileage Power Stroke engines.
Common cause
Parts:fuel injector
6
Glow plug failure causing cold-start misfire
Low severity
A failed glow plug delays combustion in that cylinder during cold starts, a standard diesel-specific misfire cause distinct from spark-ignition engines.
Common cause
Parts:glow plug
7
Air intake or charge-air leak upstream of the turbo
Medium severity
A cracked intake boot or loose clamp allows unmetered air in, upsetting the air/fuel ratio the ECM is trying to control and producing intermittent misfire codes.
Common cause
8
Low cylinder compression from worn rings, valves, or a compromised cylinder
High severity
Reduced compression in one or more cylinders prevents proper combustion and is a standard high-mileage misfire cause on any engine, diesel included.
Common cause
9
EGR valve sticking or carbon fouling
Medium severity
A stuck-open EGR valve introduces excess exhaust gas into the intake charge, diluting combustion and triggering misfire on affected cylinders.
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