P0300 on a 2021 Ford Escape Hev

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 2021 Ford Escape Hev

Ranked from 326 NHTSA owner complaints filed for this vehicle.

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1
Fuel injector crack/defect (2025 recall 25S76 / NHTSA 25V467)
High severity
The dominant pattern in this batch: a recalled fuel-injector defect produced rough idle, dropping RPMs, an engine that 'has been misfiring since purchase,' repeated 'unknown valve' failures traced to the fuel intake, and violent shaking/knocking under load.
Reported in 5 NHTSA complaints
Parts:fuel injector
2
Canister purge valve stuck open causing a vacuum/air leak
Medium severity
One owner had the purge valve confirmed stuck open, which was causing a hard start — a vacuum leak of this kind can also produce a rough-running misfire.
Reported in 1 NHTSA complaint
Parts:purge valve
3
Worn spark plugs
Low severity
Aged or fouled plugs are the most common general cause of a random misfire and the first thing to rule out.
Common cause
Parts:spark plug
4
Failing ignition coil(s)
Medium severity
A weak coil-on-plug unit misfires under load, typically confirmed by swapping coils between cylinders.
Common cause
Parts:ignition coil
5
Carbon-fouled intake valves
Low severity
Carbon buildup on the valves disrupts airflow and fuel atomization, a common contributor to random misfire.
Common cause
6
Low cylinder compression (worn rings/valves)
Medium severity
A compression test isolates a mechanical cause when spark and fuel components test fine.
Common cause

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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