P0300 on a 2021 Hyundai Palisade
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 Hyundai Palisade
Ranked from 413 NHTSA owner complaints filed for this vehicle.
- 1
Chronic oil consumption leading to low oil level and oil-starvation-related misfire
High severityThe large majority of these complaints describe burning 1-4+ quarts of oil between changes with no warning light, precisely the failure mode that starves lubrication and precedes rough running, stalling, and misfire.
Reported in 15 NHTSA complaints - 2
Worn/scored piston rings and cylinder walls with carbon buildup (known Hyundai/Kia GDI engine defect)
High severityA dealer-documented teardown found compression loss, cylinder-wall scoring/pitting, blow-by, and heavy combustion-chamber carbon buildup with active cylinder-#2 misfire; a separate complaint confirms the same defective-piston-ring pattern known across this engine family.
Reported in 2 NHTSA complaints - 3
Failing or clogged fuel injector(s)
Medium severityOne complaint documents the dealership requiring replacement of all six fuel injectors after a stalling/rough-idle pattern with the check-engine light on.
Reported in 1 NHTSA complaintParts:fuel injectors - 4
Camshaft/VVT timing actuator fault (slow cam response)
Medium severityA replacement engine set DTC P000A00 for intake camshaft position slow response, confirmed by the dealer as excessive variance between commanded and actual cam timing — a direct cause of cylinder misfire.
Reported in 1 NHTSA complaint - 5
Worn or fouled spark plugs
Medium severityDegraded plug gaps or fuel/oil-fouled electrodes weaken spark energy, producing random misfire.
Common causeParts:spark plugs - 6
Failing ignition coil(s)
Medium severityA weakening coil-on-plug drops spark energy to a single cylinder, producing a repeating misfire.
Common causeParts:ignition coil - 7
Vacuum or intake air leak
Medium severityUnmetered air entering after the MAF disrupts the air/fuel ratio enough to misfire under some conditions.
Common cause - 8
EGR valve fault
Low severityA stuck-open EGR valve admits too much exhaust gas at idle/low load, destabilizing combustion in one or more cylinders.
Common causeParts:EGR valve
Part links go to Amazon search results for this vehicle. As an Amazon Associate, WrenchConnect earns from qualifying purchases — always confirm fitment for your exact trim and engine before ordering.
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.
Rather have a pro handle it? Find a vetted local mechanic.