P0300 on a 2017 Chevrolet Malibu
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
Ranked from 720 NHTSA owner complaints filed for this vehicle.
- 1
Vacuum Pump Failure / Shattered Vacuum Pump
High severityThe vacuum pump shatters internally, sending metal debris into the engine, breaking the camshaft, and causing a sudden loss of power brake assist (hard brake pedal) and engine damage.
Reported in 5 NHTSA complaints - 2
Throttle Body / Throttle Position Sensor Failure
High severityThe throttle body or its position sensor fails, or accumulates ice/sludge, triggering a 'Reduced Engine Power' message, limp mode, and sudden loss of acceleration.
Reported in 4 NHTSA complaints - 3
Accelerator Pedal Position Sensor Failure
High severityThe accelerator pedal sensor loses connection or fails, causing the vehicle to lose motive power, stall, or enter reduced engine power mode.
Reported in 2 NHTSA complaints - 4
Turbocharger Failure
High severityThe turbocharger fails, leading to a loss of engine power, stalling, and a 'Reduced Engine Power' warning.
Reported in 1 NHTSA complaint - 5
Faulty Oxygen (O2) Sensor
Medium severityA failed or non-OEM oxygen sensor causes the vehicle to stall at lower speeds and triggers engine codes.
Reported in 1 NHTSA complaint - 6
Ignition Coil Failure
Medium severityA faulty ignition coil fails to provide the spark needed for combustion, leading to a misfire in the affected cylinder.
Common cause - 7
Worn or Damaged Spark Plugs
Low severitySpark plugs that are worn out, fouled, or improperly gapped will cause a weak or absent spark, resulting in random misfires.
Common cause - 8
Fuel Injector Issues
Medium severityClogged, leaking, or failed fuel injectors disrupt the air-fuel mixture, causing lean or rich conditions that lead to misfires.
Common cause - 9
Vacuum Leaks
Medium severityUnmetered air entering the intake manifold through a vacuum leak leans out the air-fuel mixture, causing random or multiple cylinder misfires.
Common cause
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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