P0300 on a 2015 Nissan Sentra
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 2015 Nissan Sentra
Ranked from 348 NHTSA owner complaints filed for this vehicle.
- 1
Faulty Mass Air Flow (MAF) Sensor
Medium severityA failing MAF sensor causes incorrect air/fuel mixture readings, leading to hesitation, stalling, and misfires. Look for P0101 codes accompanying the P0300.
Reported in 3 NHTSA complaints - 2
Faulty Oxygen (O2) Sensor
Medium severityA bad O2 sensor can cause improper fuel trim adjustments, resulting in unintended acceleration, hesitation, and random misfires.
Reported in 1 NHTSA complaint - 3
Worn Spark Plugs
Low severitySpark plugs degrade over time, causing weak or inconsistent spark. Inspect plugs for wear, carbon buildup, or incorrect gap.
Common cause - 4
Failing Ignition Coils
Medium severityIgnition coils can fail intermittently, especially under load or when hot, causing random misfires across multiple cylinders. Test coil resistance and check for spark.
Common cause - 5
Vacuum Leaks
Medium severityUnmetered air entering the intake manifold leans out the air/fuel mixture, causing random misfires. Check hoses, intake gaskets, and perform a smoke test.
Common cause - 6
Low Fuel Pressure / Failing Fuel Pump
High severityInadequate fuel delivery starves the engine, causing lean misfires, hesitation, and stalling. Test fuel pressure at the rail.
Common cause - 7
Clogged Fuel Injectors
Medium severityRestricted injectors prevent proper fuel atomization, leading to lean conditions and misfires. Perform an injector balance test or cleaning.
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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