P0300Powertrain
Powertrain · SAE
Random/Multiple Cylinder Misfire Detected
Meaning
The ECU detects misfires that are random or spread across several cylinders at once, rather than isolated to a single cylinder. This points to irregular combustion in the engine.
Common causes
- Worn spark plugs or ignition coils (petrol engines)
- Dirty or faulty fuel injectors
- Insufficient fuel pressure or a weak fuel pump
- Intake air or vacuum leak
- Low compression (valves, head gasket)
- Inaccurate crankshaft or camshaft position sensor
Symptoms
- Check-engine light (flashing in severe cases)
- Rough idle and vibration
- Hesitation and power loss on acceleration
- Increased fuel consumption
- Possible stalling at idle
Severity
Serious: if the warning light is flashing, stop driving, because a sustained misfire can overheat and destroy the catalytic converter.
What to do
- Read freeze-frame data and the per-cylinder misfire counters
- Check spark plugs and coils (petrol) or the injectors (diesel)
- Verify fuel pressure and look for intake leaks
- Run a compression test if ignition and fuelling are good