P0300 on a 2013 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 2013 Toyota Camry
Ranked from 301 NHTSA owner complaints filed for this vehicle.
- 1
Excessive oil consumption / Piston ring failure
High severityLow-tension piston rings can stick, leading to cylinder wall scarring, excessive oil burning, and fouled spark plugs causing misfires. Confirmed by high oil consumption and oil-fouled plugs.
Reported in 2 NHTSA complaints - 2
VVT-i Camshaft Gear failure
High severityA defective VVT gear can cause timing issues and rattling noises, leading to engine misfires or failure. Confirmed by rattling noise on startup and timing codes.
Reported in 2 NHTSA complaints - 3
Rodent damage to engine wiring
Medium severityRodents chewing on engine wiring harnesses can cause electrical shorts and open circuits, leading to misfires and check engine lights. Confirmed by visual inspection of wiring.
Reported in 1 NHTSA complaint - 4
Faulty spark plugs
Low severityWorn or fouled spark plugs are a primary cause of misfires. Look for worn electrodes or carbon buildup.
Common cause - 5
Defective ignition coils
Medium severityA failing ignition coil will not provide sufficient voltage to the spark plug, causing a misfire. Confirmed by swapping coils to see if the misfire moves.
Common cause - 6
Vacuum leaks
Medium severityUnmetered air entering the intake manifold leans out the air/fuel mixture, leading to random misfires. Confirmed by smoke testing the intake system.
Common cause - 7
Low fuel pressure / Failing fuel pump
Medium severityInadequate fuel delivery causes a lean condition and random misfires across multiple cylinders. Confirmed by testing fuel pressure at the rail.
Common cause - 8
Clogged or faulty fuel injectors
Medium severityRestricted fuel flow from dirty injectors prevents proper combustion. Confirmed by injector balance testing 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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