P0300 on a 2019 Ford F 250 Crew Cab

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 F 250 Crew Cab

Ranked from 1,151 NHTSA owner complaints filed for this vehicle.

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1
Valvetrain/rocker arm failure (6.7L Powerstroke diesel)
High severity
An owner reports rocker arm failure while driving that directly caused an engine misfire, loss of power, and abnormal noise — a known mechanical failure mode on this diesel engine.
Reported in 1 NHTSA complaint
Parts:rocker arm pushrod
2
Failing high-pressure fuel injector/injection pump
High severity
A defective fuel injector pump is reported to have caused excessive internal wear and a catastrophic failure requiring a major repair, consistent with injector/injection-pump-driven misfire.
Reported in 1 NHTSA complaint
Parts:fuel injector high-pressure fuel pump
3
Worn or carbon-fouled spark plugs
Medium severity
Plugs beyond service interval develop wide gaps or heavy carbon/oil fouling and misfire under load; pull and inspect gap and electrode wear on all cylinders.
Common cause
Parts:spark plugs
4
Failing ignition coil(s)
Medium severity
A cracked or heat-degraded coil produces a weak or intermittent spark on one cylinder; swapping the coil to a different cylinder and watching the misfire follow it confirms this.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector(s)
Medium severity
A partially clogged or dribbling injector under- or over-fuels a cylinder; an injector balance/flow test isolates the bad one.
Common cause
Parts:fuel injector
6
Vacuum or intake air leak
Medium severity
Unmetered air entering after the airflow sensor leans one or more cylinders and destabilizes idle; smoke-test the intake tract, PCV, and brake booster hoses.
Common cause
7
Carbon-fouled intake valves
Low severity
Direct-injection engines build carbon deposits on the back of the intake valves that disrupt airflow and atomization, especially at idle/low RPM; confirmed with a borescope.
Common cause
8
Low cylinder compression (worn rings/valves)
High severity
Mechanical wear that no ignition or fuel part will fix; a compression or leak-down test confirms it and points to internal engine repair.
Common cause
9
EGR system fault
Medium severity
A stuck-open EGR valve or passage dumps excess exhaust gas into the intake at idle/cruise and destabilizes combustion.
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