P0300 on a 2017 Hyundai Santa Fe Sport

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 Santa Fe Sport

Ranked from 340 NHTSA owner complaints filed for this vehicle.

Sort by:

1
PCM/ECU recalibration issue following Service Campaign 9C2 (Theta II knock-sensor software update)
Medium severity
Numerous owners report new jerking, hesitation, rough/staggering running, and near-stalls that began immediately after the 9C2 ECU software update, distinct from the underlying engine hardware defect.
Reported in 8 NHTSA complaints
2
Low compression from Theta II 2.4L GDI internal engine wear (rod bearing failure / worn rings)
High severity
This engine has a well-documented factory oil-consumption defect that wears rod bearings and rings; several owners in this batch report engine knock, limp mode, stalling, or complete engine failure tied directly to this defect, which will manifest as a misfire code before failing outright.
Reported in 7 NHTSA complaints
3
Worn or fouled spark plugs
Low severity
The most common overall cause of a random misfire code; check gap, electrode wear, and carbon fouling and replace on the recommended interval.
Common cause
Parts:spark plugs
4
Failing ignition coil(s)
Medium severity
A weakening coil produces an intermittent or cylinder-specific misfire; swap coils between cylinders to see if the misfire follows.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector(s)
Medium severity
A dirty or leaking injector disrupts the air/fuel ratio on that cylinder; injector balance/flow testing will confirm.
Common cause
Parts:fuel injector
6
Vacuum leak
Medium severity
Unmetered air entering after the MAF causes lean misfire, especially at idle; check intake boots and vacuum hoses with a smoke test.
Common cause
7
EGR valve/passage fault
Low severity
A stuck-open EGR valve or clogged passage disrupts combustion, particularly at idle and light load.
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