P0300 on a 2018 Ford Ecosport
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 2018 Ford Ecosport
Ranked from 720 NHTSA owner complaints filed for this vehicle.
- 1
Oil pump drive belt / tensioner failure starving the engine of oil pressure (recall 23S64 / NHTSA 23V905)
High severityThe overwhelming majority of this batch's complaints describe the 1.0L EcoBoost's internal oil pump drive belt or tensioner failing, oil pressure dropping, and the resulting bearing/valvetrain damage producing knocking, stalling, shaking, and misfire-like rough running; this is an open federal safety recall on this exact vehicle.
Reported in 18 NHTSA complaints - 2
Low cylinder compression from prior oil-starvation engine damage
High severitySeveral complaints describe continued shaking, stalling, or loss of power even after a recall repair or full engine replacement, consistent with residual bearing/ring or valvetrain wear producing a compression-related misfire.
Reported in 2 NHTSA complaints - 3
Worn or fouled spark plugs
Low severityEroded electrodes or carbon fouling widen the spark gap and cause intermittent misfire, particularly under load.
Common causeParts:spark plug - 4
Failing ignition coil(s)
Medium severityA weak or cracked coil drops spark energy to a cylinder; swapping coils between cylinders and watching the misfire follow confirms it.
Common causeParts:ignition coil - 5
Vacuum or turbo boost leak (1.0L EcoBoost)
Medium severityA leak in the boost or vacuum lines leans out the mixture under load and can trigger a misfire, most noticeable during acceleration.
Common cause - 6
Carbon buildup on intake valves (direct-injection engine)
Low severityDirect injection allows carbon to accumulate on the backs of the intake valves, disrupting airflow and atomization and causing a lean misfire pocket.
Common cause - 7
Faulty EGR valve
Low severityA valve stuck open over-dilutes the intake charge at idle/light load and can set a misfire code.
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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