P0300 on a 2016 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 2016 Hyundai Tucson

Ranked from 1,613 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Low cylinder compression from worn piston rings / rod-bearing wear (Theta II oil-consumption defect)
High severity
A very large share of this vehicle's complaints describe chronic oil consumption, rod-bearing knock, and internal engine seizure/replacement — worn rings and spun rod bearings lower cylinder compression enough to trigger random misfire.
Reported in 21 NHTSA complaints
2
Spark plug fouling or ignition coil failure secondary to oil consumption
Medium severity
One owner replaced spark plugs and coil packs for a persistent misfire that a shop traced to a dead cylinder, consistent with oil-fouled plugs from the engine's known oil-burning defect.
Reported in 1 NHTSA complaint
Parts:spark plugs ignition coil
3
Worn spark plugs
Low severity
Aged or improperly gapped plugs misfire under load; check gap and condition against service interval.
Common cause
Parts:spark plugs
4
Failing ignition coil(s)
Medium severity
A weak or cracked coil drops spark energy on one or more cylinders, especially noticeable under acceleration; swap-test coils cylinder to cylinder.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector
Medium severity
A partially clogged or dribbling injector unbalances air/fuel ratio on that cylinder; check injector balance/flow.
Common cause
Parts:fuel injector
6
Vacuum or intake leak
Medium severity
Unmetered air leaning out one or more cylinders can present as a misfire, particularly at idle; smoke-test the intake tract.
Common cause
7
Carbon-fouled intake valves (direct-injection buildup)
Low severity
GDI engines have no fuel washing the valves, so carbon buildup can disrupt airflow/sealing enough to cause a misfire over time.
Common cause
8
EGR valve fault (stuck open or clogged)
Low severity
Excess or erratic EGR flow at idle/light load can cause a rough-running misfire condition; check EGR operation and passages.
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