P0300 on a 2017 Kia Soul
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 2017 Kia Soul
Ranked from 270 NHTSA owner complaints filed for this vehicle.
- 1
Piston ring failure causing excessive oil consumption (known Kia Gamma/Nu engine defect)
High severityThis is a widely documented manufacturing defect on this engine family (referenced by owners against Kia TSB ENG222 and related class-action settlements) where worn piston rings let oil into the combustion chamber, fouling cylinders and eventually causing misfire or engine failure.
Reported in 4 NHTSA complaints - 2
Connecting rod bearing wear/failure from long-term oil starvation
High severityMultiple owners had a mechanic diagnose worn rod bearings (in one case with camshaft damage) after hearing a knocking noise, ultimately requiring engine replacement.
Reported in 3 NHTSA complaints - 3
Oil starvation from undetected consumption between service intervals
High severitySeveral owners found oil critically low despite recent oil changes, which triggered low oil-pressure warnings, knocking, and limp mode consistent with the known consumption defect on this engine.
Reported in 3 NHTSA complaints - 4
Sudden stutter/power loss with check-engine light indicating an active misfire event
High severitySeveral owners reported the check-engine light illuminating together with the engine stuttering or shaking and losing power, in some cases leading a mechanic to recommend full engine replacement.
Reported in 3 NHTSA complaints - 5
Seized short block with a burned/holed exhaust valve producing multi-cylinder misfire
High severityA certified technician directly diagnosed one of these vehicles with codes P0300-P0304, a seized short block, and a hole in an exhaust valve after a sudden total loss of power.
Reported in 1 NHTSA complaint - 6
Active multi-cylinder misfire confirmed by diagnostic scan with rough/stalling idle
High severityOne owner's scan tool directly confirmed all four cylinders misfiring, with the engine running rough and stalling at idle.
Reported in 1 NHTSA complaint - 7
Worn spark plugs
Low severityA standard, less platform-specific contributor to random misfire codes that should still be ruled out during diagnosis.
Common causeParts:spark plugs - 8
Failing ignition coil(s)
Medium severityA weakening coil-on-plug unit can misfire intermittently, particularly under load.
Common causeParts:ignition coil - 9
Clogged or failing fuel injector(s)
Medium severityA partially blocked or electrically weak injector starves a cylinder of fuel, producing a misfire.
Common causeParts:fuel injector
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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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