P0300
Random/Multiple Cylinder Misfire Detected
What it means
The ECM has detected misfires across more than one cylinder. Multi-cylinder misfires typically point at fuel, spark, or compression issues affecting the whole engine, not a single coil/injector.
Common causes
Listed in rough order of frequency. Verify with vehicle-specific service info before parts replacement.
- 01Failing ignition coils (especially coil-on-plug systems)
- 02Worn spark plugs across multiple cylinders
- 03Low fuel pressure (fuel pump, regulator, or filter)
- 04Vacuum leak causing lean misfire
- 05EGR valve stuck open
- 06Failed crankshaft position sensor
Affected systems
ECUs and subsystems that report or are affected by this code.
Get vehicle-specific diagnosis for P0300
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Ask the forums about P0300Critical-severity code
This code typically prevents the vehicle from starting, running normally, or operating safely. Diagnose carefully before clearing — clearing without fixing the root cause often masks deeper problems.