P0300 on a 2011 Toyota Camry Hv
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 2011 Toyota Camry Hv
Ranked from 620 NHTSA owner complaints filed for this vehicle.
- 1
Low compression from worn piston rings (documented 2AZ-FE/2AR-FE oil-consumption defect)
High severityThis engine family is widely documented (including Toyota's own warranty-extension program) to burn oil at 1 quart per 400-2000 miles with no external leak, due to worn piston rings; the resulting low ring seal/compression and oil-fouled combustion chambers are a direct path to a random/multi-cylinder misfire, and it is exactly the failure these owners describe.
Reported in 14 NHTSA complaintsParts:piston ring set - 2
Valve cover fracture damaging VVT gears and timing chain
Medium severityOne owner's vehicle was diagnosed with a fractured valve cover that damaged the VVT gears and timing chain, which can throw valve timing off enough to cause a misfire/shake.
Reported in 1 NHTSA complaintParts:timing chain - 3
Oil-fouled spark plugs from excessive oil consumption
Medium severityOil pulled past worn rings coats and fouls the plugs, causing a weak or absent spark on the affected cylinder(s).
Common causeParts:spark plugs - 4
Worn or fouled spark plugs (normal wear)
Low severityPlain wear/gap growth over time is a baseline misfire cause independent of the oil-consumption issue.
Common causeParts:spark plugs - 5
Failing ignition coil(s)
Medium severityA weak or cracked coil pack produces an intermittent misfire, especially noticeable under load or acceleration.
Common causeParts:ignition coil - 6
Vacuum leak
Low severityUnmetered air entering the intake causes a lean misfire, most noticeable at idle.
Common cause - 7
Clogged or leaking fuel injector
Low severityAn injector delivering too little (or dribbling) fuel unbalances that cylinder's air/fuel ratio.
Common causeParts:fuel injector - 8
EGR valve fault
Low severityA stuck-open EGR dilutes the intake charge enough at idle to misfire.
Common causeParts:EGR valve
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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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