P0300 on a 2019 Ford F 150 Super Crew

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 150 Super Crew

Ranked from 953 NHTSA owner complaints filed for this vehicle.

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1
Cam phaser (variable valve timing) failure / 3.5L EcoBoost "cold start rattle"
High severity
A widely documented defect (Ford CSP 21N03, TSB 19-2365) where the phaser locking pin fails to hold, throwing valve timing off enough to cause rattling, hesitation, and misfire; by far the dominant pattern in this vehicle's complaints.
Reported in 20 NHTSA complaints
Parts:cam phaser timing chain
2
Excessive oil consumption starving valvetrain lubrication
Medium severity
Low oil documented on this vehicle (oil consumption tests, 1 quart per 1000 miles) starves the phaser/timing components of pressure, aggravating rough running.
Reported in 2 NHTSA complaints
3
Worn spark plugs
Low severity
Aged plugs were replaced on this vehicle after a sputtering/vibrating complaint, though the underlying rattle persisted; still a standard misfire check.
Reported in 1 NHTSA complaint
Parts:spark plugs
4
Failing ignition coil(s)
Medium severity
A weak coil-on-plug drops spark energy to a single cylinder; coil swap test isolates it.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector(s)
Medium severity
An unbalanced injector skews one cylinder's air-fuel ratio enough to misfire.
Common cause
Parts:fuel injector
6
Vacuum leaks (intake gaskets/hoses)
Medium severity
Unmetered air entering through a cracked hose or gasket leans a cylinder enough to misfire at idle.
Common cause
Parts:intake gasket vacuum hose
7
Carbon-fouled valves
Low severity
Direct-injection engines like this EcoBoost are prone to intake-valve carbon buildup that disrupts airflow and combustion.
Common cause
8
EGR valve fault
Low severity
A stuck-open EGR valve dumps excess exhaust into the intake, causing a rough/misfiring idle.
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