Random/multiple cylinder misfire detected
What P0300 means
Your car's computer set P0300: Random/multiple cylinder misfire detected. It belongs to the ignition system and misfire group of codes. It is a generic code, so it means the same thing on every make. The check engine light usually comes on once the fault has been seen on two drives in a row. Until then it shows up as a pending code.
Can I keep driving? If the check engine light is flashing, slow down and stop driving soon. A bad misfire sends unburned fuel into the catalytic converter and can destroy it.
Common causes
- Worn spark plugs or a failing ignition coil
- Vacuum leak (cracked hose, intake gasket)
- Low fuel pressure or dirty injectors
- Low compression or a valve problem
- Bad gas
Fix the cheapest, most likely cause first. Clearing the code without a repair only turns the light off until the fault comes back.
Check it yourself
Read the freeze frame to see RPM and load when it set. Watch fuel trims: high positive trims point to a vacuum leak or fuel delivery.
Torque Deck reads P0300 with a cheap Bluetooth OBD2 adapter. It also shows the freeze frame (engine conditions at the moment the code set) and the live data you need to narrow it down.
Parts
Parts most often replaced for P0300: spark plugs and ignition coils. Confirm the cause first, and match the part to your exact engine.
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Related codes
This page explains what the code usually means. It is not a diagnosis of your car. When in doubt, ask a mechanic.