P0300 on a 2016 Dodge Journey
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 2016 Dodge Journey
Ranked from 384 NHTSA owner complaints filed for this vehicle.
- 1
Crankshaft or camshaft position sensor failure
High severityA cluster of complaints on this vehicle describe intermittent stalling, momentary loss of all electrical systems, and one explicitly diagnosed crankshaft sensor failure and cam/crank sensor codes -- a signal dropout here directly causes a misfire/stall.
Reported in 5 NHTSA complaints - 2
Camshaft / rocker arm / lifter wear (valvetrain failure)
High severityMultiple owners cite the known recall/service issue replacing rocker arms, lifters, and camshaft on this generation's engine, tied to knocking and overheating symptoms that accompany rough running.
Reported in 2 NHTSA complaints - 3
Head gasket failure allowing coolant into a cylinder
High severityOne owner's engine stalled and overheated and was diagnosed by the dealer as needing a head gasket -- coolant entering a cylinder will foul combustion and misfire.
Reported in 1 NHTSA complaintParts:head gasket - 4
Cracked plastic oil filter housing leaking oil
Medium severityAn owner described the factory oil filter housing as brittle plastic that dries out its seals and leaks hot oil in the valley of the engine; oil reaching the ignition components nearby can cause misfires.
Reported in 1 NHTSA complaintParts:oil filter housing - 5
Worn or fouled spark plugs
Low severityStandard misfire cause; inspect plugs for wear, fouling, or incorrect gap.
Common causeParts:spark plug - 6
Failing ignition coil(s)
Medium severitySwap-test a suspect coil to a known-good cylinder to confirm.
Common causeParts:ignition coil - 7
Clogged or failing fuel injector
Medium severityAn injector delivering uneven fuel produces a repeatable single or random-cylinder misfire.
Common causeParts:fuel injector - 8
Vacuum or intake leak
Medium severityUnmetered air entering the intake destabilizes combustion and can trigger a random misfire code.
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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