P0300 on a 2015 Acura Rdx
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 Acura Rdx
Ranked from 407 NHTSA owner complaints filed for this vehicle.
- 1
Misfire under acceleration/load leading to limp mode
High severityOwners describe the engine 'missing like bad gas' on acceleration and stalling into limp mode (capped near 3000 RPM) with noticeable idle shake -- classic multi-cylinder misfire symptoms.
Reported in 2 NHTSA complaints - 2
Internal engine wear / oil dilution causing rod bearing damage (Honda/Acura V6 pattern)
High severityOne owner's dealer found oil in cylinders 1 and 3 with metal debris in the oil filter, white tailpipe smoke and engine rattling -- consistent with the rod-bearing/oil-dilution failure mode documented across many 2015-era Honda/Acura V6 engines.
Reported in 1 NHTSA complaint - 3
Worn spark plugs
Low severityAged or improperly gapped plugs are the single most common P0300 cause; check plug wear/gap and carbon fouling.
Common causeParts:spark plugs - 4
Failing ignition coil(s)
Medium severityA weak or intermittently-failing coil produces exactly the random/multiple-cylinder misfire pattern this code flags; swap-test a suspect coil to a different cylinder to confirm.
Common causeParts:ignition coil - 5
Clogged or leaking fuel injector
Medium severityAn injector delivering too little or too much fuel to a cylinder causes that cylinder to misfire under load.
Common causeParts:fuel injector - 6
Vacuum leak
Medium severityUnmetered air entering after the MAF sensor leans out one or more cylinders enough to misfire, especially at idle.
Common cause - 7
Carbon-fouled intake valves
Low severityDirect-injection engines are prone to carbon buildup on the valve backs, disrupting airflow/atomization into affected cylinders.
Common cause - 8
EGR valve fault
Low severityA stuck-open EGR valve dumps excess exhaust gas into the intake at idle/low load, diluting the mixture enough 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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