P0300 on a 2020 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 2020 Hyundai Palisade
Ranked from 518 NHTSA owner complaints filed for this vehicle.
- 1
Severe oil-consumption defect (Lambda II 3.8L GDI G6DJ piston-ring bypass) starving cylinders and causing misfire
High severityAn extraordinary number of these Palisades run critically low on oil between changes with no warning light, leading to rod-bearing/piston damage, engine hesitation, rough running, and outright misfire before the engine seizes; Hyundai's own TSB/Campaign 9C9 acknowledge the piston-ring-bypass defect on this engine.
Reported in 14 NHTSA complaints - 2
Oil/carbon-fouled spark plugs from the oil-burning defect
Medium severityOne owner had spark plugs replaced twice for carbon buildup tied to the same oil-consumption defect, with shudder and check-engine-light each time until the engine ultimately failed.
Reported in 1 NHTSA complaintParts:spark plugs - 3
Worn spark plugs
Low severityFouled or gapped-out plugs fail to fire consistently, producing a random misfire code.
Common causeParts:spark plugs - 4
Failing ignition coils
Medium severityA weak or dead coil drops spark delivery to one or more cylinders.
Common causeParts:ignition coil - 5
Clogged or leaking fuel injectors
Medium severityDirty or leaking injectors disrupt the air/fuel ratio in individual cylinders.
Common causeParts:fuel injector - 6
Vacuum leaks
Medium severityUnmetered air entering through cracked hoses or gaskets leans out individual cylinders and destabilizes combustion.
Common cause - 7
EGR faults
Low severityA stuck-open EGR valve dumps excess exhaust gas into the intake, destabilizing combustion at idle.
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.