P0300 on a 2015 Toyota Camry
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 Toyota Camry
Ranked from 268 NHTSA owner complaints filed for this vehicle.
- 1
Excessive Oil Consumption / Oil Fouling
High severitySevere oil burning (often due to worn piston rings) can foul spark plugs and cause misfires. Check oil level frequently and inspect spark plugs for heavy oil ash deposits.
Reported in 5 NHTSA complaints - 2
Faulty Crankshaft Position Sensor
High severityA failing crank sensor can cause intermittent stalling, hesitation, and misfire codes by losing track of engine position. Check for related codes (e.g., P0339) and monitor RPM signal during failure.
Reported in 1 NHTSA complaint - 3
Faulty Ignition Coils
Medium severityA common cause of random misfires (P0300) across all cylinders. Look for cracked coil boots, carbon tracking, or test with a spark tester/multimeter.
Common cause - 4
Worn or Fouled Spark Plugs
Low severityWorn electrodes or carbon/oil fouling can prevent proper spark, leading to misfires. Inspect plugs for gap wear, oil, or heavy carbon deposits.
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 PCV system with a smoke machine.
Common cause - 6
Low Fuel Pressure / Failing Fuel Pump
High severityInsufficient fuel delivery causes a lean condition and random misfires under load. Verify fuel pressure with a mechanical gauge.
Common cause - 7
Clogged or Faulty Fuel Injectors
Medium severityRestricted fuel flow or poor spray patterns can cause misfires across multiple cylinders. Perform an injector balance test or check for clogged screens.
Common cause - 8
Mass Air Flow (MAF) Sensor Issues
Low severityA dirty or failing MAF sensor incorrectly reports airflow, skewing fuel trims and causing random misfires. Check MAF g/s readings on a scan tool and clean if necessary.
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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