P0300 on a 2016 Chevrolet Impala Limited

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 2016 Chevrolet Impala Limited

Ranked from 786 NHTSA owner complaints filed for this vehicle.

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1
Cracked piston / low cylinder compression
High severity
Two owners had a mechanic trace a persistent misfire (one specifically a cylinder-1 misfire code) directly to a cracked piston, described by one as a known issue for this model year and engine.
Reported in 2 NHTSA complaints
2
Valve-train/camshaft damage from an oil-starved brake-booster vacuum pump
High severity
One owner's engine-oil-lubricated brake-booster vacuum pump clogged its inline oil screen and ran dry, sending debris into the top of the engine and damaging the camshafts and timing chain -- damage that can throw off valve timing and produce a misfire.
Reported in 1 NHTSA complaint
3
Worn spark plugs
Low severity
A common, low-cost wear item; degraded plugs are one of the most frequent causes of a random-cylinder misfire code.
Common cause
Parts:spark plugs
4
Failing ignition coil
Medium severity
A weak coil-on-plug unit produces a repeatable misfire, often worsening when hot or under load.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector
Medium severity
An injector delivering an incorrect fuel charge to one cylinder causes a repeatable misfire on that cylinder.
Common cause
Parts:fuel injector
6
Vacuum leak
Medium severity
Unmetered air entering the intake leans out one or more cylinders enough to misfire, especially noticeable at idle.
Common cause
7
Carbon-fouled intake valves
Low severity
Carbon buildup on the intake valves disrupts airflow and atomization enough to cause an intermittent misfire, especially at idle.
Common cause

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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