P0300 on a 2020 Ford Explorer

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 Explorer

Ranked from 1,171 NHTSA owner complaints filed for this vehicle.

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1
Coolant intrusion into a cylinder from head-gasket failure
High severity
One owner was told of possible engine coolant in cylinders 2 and 3, tied to known EcoBoost head-gasket issues — coolant entering a cylinder will foul the plug and kill combustion on that cylinder.
Reported in 1 NHTSA complaint
Parts:head gasket
2
Engine damage/oil ingestion from a failing turbocharger
High severity
One owner's turbo was found pulling oil out of the oil tank and into the engine, damaging it — oil-fouled cylinders will misfire before the underlying turbo failure is caught.
Reported in 1 NHTSA complaint
Parts:turbocharger
3
Worn or fouled spark plugs
Low severity
Standard top cause of random/multi-cylinder misfire on any port/direct-injection V6.
Common cause
Parts:spark plugs
4
Failing ignition coil(s)
Medium severity
A weakening coil-on-plug unit drops spark energy under load, especially on the boosted EcoBoost engines in this fleet.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injectors
Medium severity
An injector delivering too little (or dribbling) fuel produces a chronically misfiring cylinder.
Common cause
Parts:fuel injector
6
Vacuum or intake leaks
Medium severity
Unmetered air entering the intake after the MAF leans and destabilizes combustion enough to misfire.
Common cause
7
Carbon-fouled intake valves
Low severity
Direct-injection EcoBoost engines lack fuel washing the intake valves, so carbon buildup there disrupts airflow into individual cylinders over time.
Common cause
8
EGR valve/passage fault
Medium severity
A stuck-open EGR valve over-dilutes the intake charge on one or more cylinders, causing a misfire particularly at idle/light load.
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