P0300 on a 2015 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 2015 Ford Explorer
Ranked from 1,751 NHTSA owner complaints filed for this vehicle.
- 1
Internal Water Pump Failure / Coolant Intrusion
High severityThe water pump on these engines is internally mounted and driven by the timing chain. When it fails, it can leak coolant internally, causing overheating, engine damage, and misfires.
Reported in 9 NHTSA complaints - 2
Turbocharger Failure
High severityFailure of the turbochargers can cause loss of power, smoke from the exhaust, and engine misfires due to improper air/fuel mixture or oil ingestion.
Reported in 2 NHTSA complaints - 3
Timing Chain / Camshaft Synchronization Issues
High severityStretching of the timing chain or failure of the VCT phasers can cause camshaft misalignment (codes P0018/P0017), leading to erratic idle, stalling, and random misfires.
Reported in 1 NHTSA complaint - 4
Fuel Injector Issues
Medium severityClogged, leaking, or failing fuel injectors can cause an improper spray pattern or incorrect fuel delivery, leading to misfires. One complaint noted fuel injector cleaner helped erratic RPMs.
Reported in 1 NHTSA complaint - 5
Worn Spark Plugs
Low severitySpark plugs naturally wear out over time, leading to a weak spark that fails to ignite the air/fuel mixture properly, causing random misfires.
Common cause - 6
Faulty Ignition Coils
Medium severityIgnition coils can degrade or fail, especially under load, preventing the spark plug from firing and resulting in a misfire condition.
Common cause - 7
Vacuum Leaks / Intake Manifold Gasket Leaks
Medium severityUnmetered air entering the engine through a vacuum leak or faulty intake gasket leans out the air/fuel mixture, causing random or multiple cylinder misfires.
Common cause - 8
Low Fuel Pressure / Failing Fuel Pump
Medium severityIf the fuel pump cannot maintain adequate pressure, the engine will run lean, causing random misfires across multiple cylinders.
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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