P0300 on a 2017 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 2017 Ford F 350 Supercab

Ranked from 560 NHTSA owner complaints filed for this vehicle.

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1
Fuel injector damage/clogging from CP4 high-pressure pump failure showering metal through the fuel system
High severity
This truck's well-documented CP4 high-pressure pump failure mode sheds metal shavings into the fuel rail and injectors, directly causing rough running/misfire on the affected cylinders; one complaint also notes resulting EGR valve damage.
Reported in 2 NHTSA complaints
Parts:fuel injectors high-pressure fuel pump
2
Low fuel rail pressure from a failing/weakening high-pressure fuel pump
High severity
Intermittent surge/bucking under load with no stored DTC is consistent with momentary fuel-pressure drop from a degrading CP4 pump, which produces misfire-like roughness on a diesel.
Reported in 1 NHTSA complaint
Parts:high-pressure fuel pump
3
EGR valve fault/damage causing rough combustion
Medium severity
Metal contamination from the failed fuel pump was documented to have damaged the EGR valve on this platform, which can upset combustion and register as a misfire.
Reported in 1 NHTSA complaint
Parts:EGR valve
4
Low cylinder compression from internal engine wear (rod bearing failure)
High severity
A rod-bearing failure on this 6.7L Powerstroke caused audible knocking and required a full long-block replacement; the resulting compression loss on the affected cylinder(s) can register as a misfire before catastrophic failure.
Reported in 1 NHTSA complaint
5
Glow plug failure (cold-start misfire)
Low severity
A failed or weak glow plug delays combustion in that cylinder on cold starts, a common diesel-specific misfire cause not present on gasoline engines.
Common cause
Parts:glow plug
6
Injector O-ring/seal leak or return-line fault
Medium severity
A leaking injector seal lets fuel or air escape the injection event, causing an individual-cylinder misfire that a compression or leak-down test on the injector circuit will confirm.
Common cause
Parts:fuel injector
7
Air or water intrusion / contaminated fuel
Medium severity
Air pulled into the low-pressure side or water-contaminated diesel disrupts injection timing and combustion, producing an intermittent misfire.
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

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