P0300 on a 2015 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 2015 Ford F 250 Supercab

Ranked from 296 NHTSA owner complaints filed for this vehicle.

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1
Rough/incomplete combustion during DPF regeneration cycle
Medium severity
Numerous 6.7L Power Stroke owners describe knocking, shaking, and power loss specifically during the "cleaning exhaust filter" regen event — a known fueling-strategy issue addressed by Ford TSB 15-0088.
Reported in 4 NHTSA complaints
2
Fuel contamination from failed high-pressure (CP4) fuel pump
High severity
Owners report a fuel-pump failure code with metal shards/shavings found in the fuel system and engine oil; debris-starved or scored injectors misfire and can cascade into full engine failure.
Reported in 3 NHTSA complaints
Parts:high-pressure fuel pump fuel injectors fuel filter
3
Low cylinder compression from valvetrain failure (dropped/stuck valve)
High severity
Multiple reports describe a broken valve spring dropping a valve, or a stuck exhaust valve, punching the piston/cylinder wall — a cylinder with holed compression will misfire before it fails outright.
Reported in 2 NHTSA complaints
Parts:valve spring exhaust valve
4
Broken/failed glow plug
High severity
One owner's catastrophic engine failure was traced to broken glow plugs; a dead or fractured glow plug causes hard cold-start misfire on that cylinder and can drop metal into it.
Reported in 1 NHTSA complaint
Parts:glow plug
5
Clogged or leaking fuel injector
Medium severity
A partially clogged or dribbling injector under- or over-fuels its cylinder, producing a steady misfire on that cylinder.
Common cause
Parts:fuel injector
6
Low compression from worn piston rings or valves
High severity
General wear reduces cylinder sealing enough that combustion is incomplete, showing up as a random/multiple-cylinder misfire.
Common cause
7
EGR passage/valve carbon fouling
Low severity
Excess or erratic EGR flow dilutes the intake charge unevenly and can misfire cylinders, especially at idle.
Common cause
Parts:EGR valve
8
Air in the fuel system from a failing lift pump or loose fitting
Medium severity
Intermittent air ingestion starves injectors momentarily, producing a stumble/misfire that often clears itself.
Common cause
Parts:fuel lift pump

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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