P0300 on a 2018 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 2018 Ford F 150 Super Crew
Ranked from 1,835 NHTSA owner complaints filed for this vehicle.
- 1
Cam phaser failure ("cam phaser rattle")
High severityThe dominant, well-documented failure on this EcoBoost engine — worn cam phasers cause a cold-start rattle/knock and rough, misfire-like running as valve timing drifts; confirmed by multiple dealers as the cause of the noise and rough operation.
Reported in 15 NHTSA complaints - 2
Excessive engine oil consumption
Medium severityMultiple owners cite abnormal oil consumption (TSB 19-2365) on this engine; oil pulled past worn rings can foul plugs and contribute to misfire over time.
Reported in 3 NHTSA complaints - 3
Low cylinder compression from internal engine wear
High severityOne owner's cylinder #6 misfire was traced to progressively falling compression (eventually 0%) despite spark plug, injector, and coil replacement, pointing to a mechanical (ring/valve) rather than ignition cause.
Reported in 1 NHTSA complaint - 4
Worn spark plugs
Low severityEroded electrodes widen the spark gap and misfire under boost/load; inspect gap and wear at the service interval.
Common causeParts:spark plug - 5
Failing ignition coil(s)
Medium severityA weakening coil-on-plug misfires intermittently, especially under boost; swap-test between cylinders to isolate.
Common causeParts:ignition coil - 6
Clogged or leaking fuel injector
Medium severityA restricted or dribbling injector unbalances one cylinder's air/fuel ratio enough to misfire; check injector balance/flow.
Common causeParts:fuel injector - 7
Vacuum or charge-air leak
Medium severityOn a turbocharged engine, a boost/vacuum leak leans a cylinder or bank enough to misfire under load; smoke-test the intake and charge piping.
Common cause - 8
EGR valve/passage fault
Low severityExcess or uneven EGR flow dilutes the charge and can trigger misfire at idle or light throttle.
Common causeParts: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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