P0300 on a 2020 Ford F 150 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 2020 Ford F 150 Supercab

Ranked from 506 NHTSA owner complaints filed for this vehicle.

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1
Cam phaser (VCT actuator) failure
High severity
This truck's engine shows a strong repeated pattern of cold-start rattle/knock, rough idle, and check-engine light that dealers diagnosed as failed cam phasers -- a well-known Ford timing-actuator issue that disrupts valve timing enough to misfire.
Reported in 7 NHTSA complaints
Parts:cam phaser timing chain
2
Excessive oil consumption leading to fouled plugs / worn rings
High severity
Several owners on this truck reported abnormally high oil consumption (up to 2 quarts per 1,300 miles), with one case ending in engine replacement after metal was found in the oil -- a known issue that can foul plugs and drop compression.
Reported in 3 NHTSA complaints
Parts:spark plug piston rings
3
Ignition coil failure, sometimes worsened by moisture intrusion
Medium severity
One owner's intermittent engine shutdown occurred while driving in heavy rain, a pattern consistent with water finding its way into a coil boot/pack and causing a misfire.
Reported in 1 NHTSA complaint
Parts:ignition coil
4
Fuel delivery unable to keep up at wide-open throttle
Medium severity
One owner described the truck stuttering specifically at wide-open throttle, consistent with the fuel pump/pressure system falling behind under peak demand.
Reported in 1 NHTSA complaint
Parts:fuel pump
5
Worn or fouled spark plugs
Low severity
Standard misfire cause; pull and inspect plugs for wear, fouling, or improper gap.
Common cause
Parts:spark plug
6
Fuel injector fault
Medium severity
A dirty or failing injector delivers uneven fuel to a cylinder, producing a repeatable misfire under load.
Common cause
Parts:fuel injector
7
Vacuum or intake leak
Medium severity
Unmetered air entering the intake destabilizes air/fuel ratio and can trigger random misfire codes.
Common cause
8
EGR valve fault
Low severity
Excess recirculated exhaust gas at idle or light load can destabilize combustion enough to misfire.
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