P0300 on a 2019 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 2019 Acura Rdx

Ranked from 431 NHTSA owner complaints filed for this vehicle.

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1
Turbo intercooler condensation ingestion (Acura TSB 20-053)
High severity
In wet/humid driving, water condenses in the RDX 2.0T's front-mount intercooler piping and gets drawn into the cylinders on acceleration, causing a multi-cylinder misfire with a flashing MIL and limp mode -- this batch has 9 owners reporting exactly that rain-triggered pattern, and Acura's own bulletin prescribes replacing the intercooler/hoses and reflashing the PCM.
Reported in 9 NHTSA complaints
Parts:intercooler intercooler hose/pipe
2
Head gasket failure allowing coolant into the cylinders
High severity
Six owners report a failed head gasket letting coolant leak into cylinders 2/3, producing a startup sputter/choppy shudder and overheating -- coolant-fouled combustion is a direct misfire cause.
Reported in 6 NHTSA complaints
Parts:head gasket
3
Failing/recalled in-tank fuel pump
High severity
Six owners had the fuel pump replaced or awaited replacement under NHTSA recalls tied to this platform; intermittent fuel starvation from a failing pump can present as rough running/misfire before a full stall.
Reported in 6 NHTSA complaints
Parts:fuel pump
4
Cracked cylinder head (possible casting defect)
High severity
One owner's mechanic found a cracked cylinder head with no prior warning, suspected to be a manufacturing defect, which lets compression/coolant escape from the affected cylinder.
Reported in 1 NHTSA complaint
Parts:cylinder head
5
Failing ignition coil and/or spark plug
Medium severity
One owner's dealer diagnostics found a bad ignition coil and spark plug causing a sudden limp-mode event -- the textbook misfire pair on any engine.
Reported in 1 NHTSA complaint
Parts:ignition coil spark plug
6
Worn spark plugs (routine wear)
Low severity
Standard misfire cause; check gap/electrode wear against the service interval.
Common cause
Parts:spark plugs
7
Vacuum/intake leak
Medium severity
Unmetered air leans out a cylinder and produces a misfire, especially at idle.
Common cause
8
Carbon-fouled intake valves (direct injection)
Low severity
GDI engines have no port fuel to wash the valves, so carbon buildup restricts and unevenly fills cylinders over time.
Common cause
9
EGR valve fault
Low severity
A stuck-open EGR valve over-dilutes the intake charge at idle/low load, causing a rough-running misfire.
Common cause
Parts: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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Matching symptoms

Car Runs Rough Flashing Check Engine Light