P0300 on a 2019 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 2019 Ford Explorer

Ranked from 285 NHTSA owner complaints filed for this vehicle.

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1
Internal Water Pump Failure
High severity
The internal water pump fails, leaking coolant into the engine oil or causing overheating, which can lead to catastrophic engine failure or stalling.
Reported in 3 NHTSA complaints
2
Faulty Fuel Pump / Fuel Injectors
High severity
Multiple complaints describe stalling, loss of power, or failure to start, with dealer diagnosis pointing to a faulty fuel pump and/or fuel injectors.
Reported in 2 NHTSA complaints
3
Faulty Spark Plugs / Ignition Coils
Medium severity
A fractured spark plug or worn ignition components can cause misfires, stalling, and trigger a P0300 code.
Reported in 1 NHTSA complaint
4
Timing Chain Failure / Stretch
High severity
Timing chain issues can cause engine stalling, rattling noises, and misfires by throwing off engine timing.
Reported in 1 NHTSA complaint
5
Vacuum Leak / Intake Manifold Disconnection
Medium severity
A disconnected air intake manifold or vacuum leak introduces unmetered air, causing a lean condition and random misfires.
Reported in 1 NHTSA complaint
6
Faulty MAP Sensor
Medium severity
A failing Manifold Absolute Pressure (MAP) sensor can provide incorrect engine load data, leading to improper fueling and misfires.
Reported in 1 NHTSA complaint
7
Exhaust Leak / Improper Welds
High severity
Improper or incomplete welds on the exhaust system can cause exhaust leaks, which may affect O2 sensor readings and fuel trim, potentially causing misfires.
Reported in 1 NHTSA complaint
8
Low Fuel Pressure / Fuel Line Issues
High severity
Improperly attached fuel lines or clamps from the factory can cause fuel leaks and low fuel pressure, leading to misfires.
Reported in 1 NHTSA complaint
9
Carbon Buildup on Intake Valves
Medium severity
Direct injection engines (like the EcoBoost) are prone to carbon buildup on intake valves, restricting airflow and causing random misfires.
Common cause
10
Faulty Mass Air Flow (MAF) Sensor
Medium severity
A dirty or failing MAF sensor incorrectly measures incoming air, causing improper air-fuel mixtures and random misfires.
Common cause
11
EGR Valve Malfunction
Medium severity
A stuck open Exhaust Gas Recirculation (EGR) valve can introduce too much exhaust gas into the intake, causing a rough idle and misfires.
Common cause
12
Engine Mechanical Issues (Low Compression)
High severity
Internal engine wear, blown head gaskets, or burnt valves can cause low compression in multiple cylinders, resulting in a P0300 code.
Common cause

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