P0300 on a 2019 Chrysler Pacifica

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 Chrysler Pacifica

Ranked from 338 NHTSA owner complaints filed for this vehicle.

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1
Head gasket failure letting coolant into the cylinders (3.6L Pentastar)
High severity
Repeatedly reported on this exact vehicle: coolant disappears with no external leak, the engine overheats, and a misfire code follows soon after — confirmed at the dealer/shop as a blown or cracked head gasket in multiple cases.
Reported in 10 NHTSA complaints
Parts:head gasket
2
Camshaft/valve-train fault (metal debris or stuck intake valve, Pentastar 3.6L)
High severity
Two owners had cylinder-specific misfire codes traced to a valve-train problem — one to the camshaft shedding metal shavings into the cylinders, the other to an intake valve stuck in low lift (code P105C) — with plug/coil/VVT-solenoid swaps failing to fix it.
Reported in 2 NHTSA complaints
Parts:camshaft valve lifter
3
Worn or fouled spark plugs
Medium severity
Still the most common overall cause of a random/multiple misfire code; owners here had plugs replaced as a first (sometimes insufficient) fix.
Common cause
Parts:spark plug
4
Failing ignition coil(s)
Medium severity
A weakening coil-on-plug unit drops spark energy on one or more cylinders, especially under load.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector(s)
Medium severity
A partially clogged or dribbling injector starves or floods an individual cylinder, producing a repeatable misfire on that cylinder.
Common cause
Parts:fuel injector
6
Vacuum or intake air leak
Medium severity
Unmetered air entering after the MAF sensor leans out one or more cylinders enough to misfire, especially at idle.
Common cause
7
Carbon-fouled intake valves
Low severity
Direct-injection engines like the Pentastar 3.6L are prone to carbon buildup on the backs of the intake valves, disrupting airflow and combustion.
Common cause
8
EGR valve fault
Low severity
A stuck-open EGR valve dumps excess exhaust gas into the intake at idle, diluting the charge enough to cause a misfire.
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