P0300 on a 2013 Hyundai Elantra
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 2013 Hyundai Elantra
Ranked from 1,325 NHTSA owner complaints filed for this vehicle.
- 1
Internal engine failure / Piston slap
High severityA known issue with the 1.8L Nu engine where piston slap or connecting rod bearing failure causes severe knocking, metal shavings in oil, and sudden engine stalling or seizure.
Reported in 11 NHTSA complaints - 2
Defective ABS Module (Recall 251 / 23V651000)
High severityThe ABS module leaks brake fluid, causing electrical shorts and potential engine compartment fires, which can lead to engine stalling and multiple warning lights.
Reported in 6 NHTSA complaints - 3
Faulty Camshaft Position Sensor
High severityThe engine shuts off while driving, has trouble restarting, and the RPM gauge stays at zero, often triggering a camshaft code.
Reported in 2 NHTSA complaints - 4
Faulty Crankshaft Position Sensor
High severityThe vehicle loses power, idles very low, stalls, and the tachometer registers zero RPMs even when accelerating.
Reported in 1 NHTSA complaint - 5
Worn Spark Plugs
Medium severityA standard cause for random/multiple cylinder misfires (P0300) due to worn electrodes failing to ignite the air/fuel mixture properly.
Common cause - 6
Faulty Ignition Coils
Medium severityA common generic cause for P0300 where failing ignition coils cannot provide sufficient voltage to the spark plugs, resulting in misfires.
Common cause - 7
Vacuum Leak
Medium severityUnmetered air entering the intake manifold leans out the air/fuel mixture, causing random misfires across multiple cylinders.
Common cause - 8
Low Fuel Pressure / Failing Fuel Pump
Medium severityInsufficient fuel delivery prevents proper combustion, leading to random misfires and a P0300 code.
Common cause
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.
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