P0300 on a 2017 Hyundai Tucson

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 Hyundai Tucson

Ranked from 1,076 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Premature rod-bearing wear / internal engine damage from Hyundai's documented Nu 2.0L & Gamma 1.6T GDI oil-consumption defect
High severity
The dominant pattern in this batch: metal shavings/flakes in the oil, knocking, and severe oil consumption (NHTSA Recall 21V727000, DTC P1326 knock-sensor detection, Theta II engine litigation) progressively degrades compression and combustion until cylinders misfire or the engine seizes outright.
Reported in 20 NHTSA complaints
2
Burned/worn exhaust valve
High severity
One owner's sudden loss of power at highway speed was diagnosed as a burned exhaust valve requiring cylinder head and valve replacement -- a classic persistent-single-cylinder-misfire cause.
Reported in 1 NHTSA complaint
Parts:exhaust valve
3
Failing ignition coil(s)
Medium severity
One owner paid out of pocket to replace ignition coils when the check engine light first came on, before the engine later began knocking and needing replacement.
Reported in 1 NHTSA complaint
Parts:ignition coil
4
Worn or incorrect-fit spark plugs
Low severity
A repair shop initially replaced spark plugs (two of which turned out to be an incorrect fit) on this same vehicle before the underlying rod-bearing failure surfaced.
Reported in 1 NHTSA complaint
Parts:spark plug
5
Vacuum or intake air leak
Medium severity
Unmetered air leaning out a cylinder can produce an isolated misfire under load.
Common cause
6
Clogged or leaking fuel injector
Medium severity
A dirty or dribbling injector under/over-fuels a cylinder, causing a steady misfire on that cylinder.
Common cause
Parts:fuel injector
7
EGR valve fault
Low severity
A stuck-open EGR valve over-dilutes the intake charge, especially at idle, producing a rough-running misfire.
Common cause
Parts: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.

Matching symptoms

Car Runs Rough Flashing Check Engine Light