P0300
Random/Multiple Cylinder Misfire Detected
The engine is misfiring in more than one cylinder randomly.
The crankshaft position sensor detects variations in crankshaft speed that indicate misfires. P0300 means multiple cylinders are misfiring, not just one. This points to a cause that affects all cylinders such as fuel delivery, intake leak, or ignition timing issue rather than a single-cylinder problem.
Symptoms
Common Causes
Worn spark plugs
HIGHPlugs past their service life cause weak spark across all cylinders.
Vacuum leak
HIGHLarge leak causes lean misfires across multiple cylinders.
Low fuel pressure
MEDIUMAll injectors receive insufficient fuel.
Ignition coil pack failure
MEDIUMOn waste-spark systems, one coil fires two cylinders.
Step-by-Step Diagnosis
Check misfire counters
mediumUse scanner mode $06 to see which cylinders are misfiring most.
Inspect spark plugs
mediumRemove and inspect all spark plugs for wear, fouling, or incorrect gap.
Check ignition coils
mediumTest resistance of each coil. Swap coils between cylinders to see if misfire moves.
Check fuel pressure
hardLow fuel pressure will cause lean misfires on all cylinders.
Frequently Asked Questions
The information on this page is provided for general educational and reference purposes only. ErrorCodes is not a substitute for professional automotive diagnosis or repair. Diagnostic trouble codes indicate areas for further investigation and do not definitively identify the failed component. The same code can have different causes depending on your specific vehicle, its history, and conditions. Always consult a qualified, certified mechanic before performing repairs. ErrorCodes assumes no liability for any repairs made based on information found on this site.