P0300 on a 2017 Ford F 350 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 2017 Ford F 350 Regular Cab

Ranked from 560 NHTSA owner complaints filed for this vehicle.

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1
High-pressure fuel pump (CP4) failure showering metal debris through the fuel system
High severity
One owner had a confirmed high-pressure fuel pump failure that distributed metal debris through the fuel system, damaging injectors and causing the engine to shut off on acceleration — a documented failure mode on the 6.7L Powerstroke's CP4 pump.
Reported in 1 NHTSA complaint
Parts:high-pressure fuel pump fuel injector fuel filter fuel lines
2
Failing or fouled fuel injector(s)
High severity
A weak, clogged, or dribbling diesel injector under- or over-fuels its cylinder, producing an uneven-contribution/misfire code; one owner noted a fuel-injector warning light appear shortly before a fuel-system failure.
Reported in 1 NHTSA complaint
Parts:fuel injector
3
Worn rod bearings / low compression from internal wear
High severity
One owner had the engine begin knocking with rod bearing wear diagnosed on the 6.7L Powerstroke, requiring a long-block replacement — mechanical wear that lowers compression will show up as a misfire/rough-running code.
Reported in 1 NHTSA complaint
4
Water or debris contamination in the diesel fuel
Medium severity
Diesel injection systems are extremely sensitive to contamination; even small amounts of water or particulate in the fuel can disrupt combustion enough to register as a cylinder misfire.
Common cause
5
Glow plug failure (cold-start misfire)
Low severity
A failed glow plug on one or more cylinders can prevent a clean cold-start combustion event, which the PCM may log as a misfire until the engine warms up.
Common cause
Parts:glow plug
6
Air ingestion in the fuel system (leaking supply line or filter housing seal)
Medium severity
A small air leak on the suction side of the lift pump causes inconsistent injector fueling and rough running/misfire, especially under load.
Common cause
Parts:fuel lines fuel filter housing
7
EGR valve fault / excessive carbon buildup
Low severity
A stuck or heavily carboned EGR valve can over-dilute the intake charge, especially at idle and low load, producing a misfire pattern.
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