P0300 on a 2017 Chevrolet Malibu Eco

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 2017 Chevrolet Malibu Eco

Ranked from 687 NHTSA owner complaints filed for this vehicle.

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1
Brake vacuum pump failure shedding metal into the engine (camshaft/timing damage)
High severity
Five separate owners describe the electric brake-booster vacuum pump exploding/breaking apart and sending metal debris into the engine, cracking or breaking the camshaft and timing chain -- a well-documented pattern on this Malibu that produces rough running and misfire.
Reported in 5 NHTSA complaints
2
Piston/piston-pin wear causing cylinder misfire
High severity
One owner's P0301 (cylinder 1 misfire) was traced by the dealer to a broken plastic piston-pin retainer, a known wear issue on this engine that the dealer said could only be fixed by replacing pistons or the whole engine.
Reported in 1 NHTSA complaint
3
Worn or blown spark plug
Medium severity
An independent mechanic diagnosed a blown spark plug as the cause of engine seizure and stall on this vehicle.
Reported in 1 NHTSA complaint
Parts:spark plugs
4
Failing ignition coil(s)
Medium severity
A weak or cracked coil loses spark energy under load, producing an intermittent single- or multi-cylinder misfire.
Common cause
Parts:ignition coil
5
Clogged or leaking fuel injector
Medium severity
A partially clogged or dribbling injector disrupts the air-fuel ratio in one cylinder enough to cause a misfire under load.
Common cause
Parts:fuel injector
6
Vacuum or intake leak
Medium severity
Unmetered air entering the intake after the MAF sensor skews the air-fuel ratio and can trigger a misfire, especially at idle.
Common cause
Parts:intake gasket vacuum hose
7
Carbon-fouled intake valves
Low severity
Direct-injection engines like this one are prone to carbon buildup on the intake valves, disrupting airflow and atomization into affected cylinders.
Common cause
8
EGR valve fault
Low severity
A stuck-open EGR valve admits excess exhaust gas at idle/low load, diluting the mixture enough to cause a 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