P0300
Random/Multiple Cylinder Misfire Detected
Powertrain · Generic (all makes)System: Ignition + Fuel Delivery
Stop driving. Risk of damage or a breakdown.
Likely causes
- Worn spark plugs or a failing ignition coil
- Vacuum leak
- Low fuel pressure or a clogged injector
- Low compression (burnt valve, worn rings)
What to check first
Find which cylinders misfire with live data, then check plugs and coils first. A flashing check-engine light means unburnt fuel is reaching the catalytic converter: stop driving.
Typical repair cost
$100 – $900
Independent-shop parts and labor for the usual fix. Your price depends on the actual cause and the vehicle.
Next step
General information, not a diagnosis of your vehicle. Repair costs are typical shop ranges, not quotes.