P0300 on a 2010 Chevrolet Impala

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 2010 Chevrolet Impala

Ranked from 441 NHTSA owner complaints filed for this vehicle.

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1
Recurring engine vibration/rough-running condition
Medium severity
One owner reports the engine shaking back-and-forth again even after a full engine replacement, a symptom pattern consistent with an ongoing misfire rather than a one-off failure.
Reported in 1 NHTSA complaint
Parts:spark plugs ignition coil
2
Mass airflow (MAF) sensor fault
Medium severity
One complaint links an engine shutdown event to a suspected air mass flow sensor problem, which can cause an incorrect air/fuel mixture and rough running.
Reported in 1 NHTSA complaint
Parts:mass airflow sensor
3
Worn or fouled spark plugs
Medium severity
A standard high-mileage misfire cause on this V6; worn electrodes misfire under load as the gap widens.
Common cause
Parts:spark plugs
4
Failing ignition coil
Medium severity
A weak or intermittent coil produces a misfire on the affected cylinder(s), a standard cause on this engine family.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector
Medium severity
A partially clogged or dripping injector disrupts the fuel charge to that cylinder, a standard misfire cause.
Common cause
Parts:fuel injector
6
Vacuum leak
Medium severity
Cracked intake/vacuum hoses let in unmetered air, upsetting the air/fuel ratio and causing a rough idle or misfire.
Common cause
7
Low cylinder compression from worn rings or valves
High severity
A standard high-mileage misfire cause; oil consumption reported on this vehicle can be a symptom of the same ring wear.
Common cause
8
EGR valve sticking
Medium severity
A stuck-open EGR valve over-dilutes the intake charge with exhaust gas, a standard misfire contributor.
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