P0300 on a 2015 Ford F 250 Regular Cab
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 Regular Cab
Ranked from 296 NHTSA owner complaints filed for this vehicle.
- 1
High-pressure (CP4) fuel injection pump failure/contamination
High severityOwners report a fuel-pump fault code with engine sputtering, metal shavings found in the oil, and white smoke with a sudden loss of power - all consistent with the well-documented CP4 pump failures on this 6.7L Power Stroke contaminating the injection system and causing rough/misfiring combustion.
Reported in 4 NHTSA complaints - 2
Rough combustion/over-fueling during DPF regeneration cycles
Medium severitySeveral owners describe knocking, shaking, and significant power loss specifically during the exhaust regen cycle, consistent with excess post-injection fueling causing irregular combustion.
Reported in 4 NHTSA complaints - 3
Low compression from valvetrain/piston damage
High severityOwners report a dropped valve from a broken valve spring holing the piston, and a stuck exhaust valve driving a rod through the piston and cylinder wall - both leave the affected cylinder unable to fire.
Reported in 2 NHTSA complaints - 4
Glow plug failure
High severityOne owner's catastrophic engine failure was directly attributed to broken glow plugs, which cause cold-start misfire and can shed debris internally on this engine.
Reported in 1 NHTSA complaintParts:glow plug - 5
Fuel injector fouling/coking
Medium severityDiesel injectors accumulate carbon deposits over time that disrupt the spray pattern and cause a cylinder to run rough or misfire.
Common causeParts:fuel injector - 6
EGR valve fault
Low severityA stuck or heavily sooted EGR valve over-dilutes the intake charge, causing rough idle and misfire.
Common causeParts:EGR valve - 7
Intake or charge-air (boost) leak
Low severityA cracked charge-air cooler hose or boot admits unmetered air, upsetting combustion enough to misfire under load.
Common causeParts:charge air hose
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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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