P0300 on a 2020 Ford F 150 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 2020 Ford F 150 Regular Cab
Ranked from 506 NHTSA owner complaints filed for this vehicle.
- 1
Cam phaser failure / timing chain rattle (5.0L Coyote VCT phasers)
High severityThis is a well-documented failure on the 5.0L: worn variable cam timing phasers rattle on start-up and let valve timing drift, which produces a misfire; multiple owners had phasers replaced under Ford Campaign 21B10/21N03 or Customer Satisfaction Program.
Reported in 6 NHTSA complaints - 2
Excessive oil consumption (5.0L design issue)
Medium severitySeveral owners document the engine burning several quarts of oil between changes with a confirmed dealer oil-consumption test; low oil and oil-fouled plugs directly cause a misfire.
Reported in 4 NHTSA complaintsParts:spark plug - 3
Internal engine failure (rod/crankshaft damage)
High severitySeveral complaints describe catastrophic engine failure, including a cracked crankshaft between cylinders, which will produce severe misfire symptoms immediately beforehand.
Reported in 3 NHTSA complaints - 4
Worn spark plugs
Low severityAged or gapped-out plugs are the most common general cause of a random misfire on any engine.
Common causeParts:spark plug - 5
Failing ignition coil(s)
Medium severityA weak or cracked coil-on-plug unit produces an intermittent spark that reads as a misfire, usually isolated to one cylinder.
Common causeParts:ignition coil - 6
Clogged or leaking fuel injector
Low severityA dirty or leaking injector starves or floods a cylinder enough to misfire.
Common causeParts:fuel injector - 7
Vacuum or intake leak
Low severityUnmetered air entering after the MAF leans out a cylinder enough to misfire, particularly at idle.
Common cause - 8
EGR valve fault
Low severityA stuck-open EGR dilutes the intake charge and can cause rough idle and misfire.
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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