P0300
P0300 Random/Multiple Cylinder Misfire
P0300 is a generic OBD2 powertrain code for random or multiple cylinder misfire. Unlike P0301 through P0308, it does not point to one specific cylinder, so the cause can be ignition, fuel, air, sensor, or mechanical.
How urgent is P0300?
If the check engine light is flashing or the car is shaking badly, avoid driving. A severe misfire can overheat and damage the catalytic converter.
Common symptoms
- Flashing or steady check engine light
- Rough idle
- Shaking under acceleration
- Loss of power
- Fuel smell from exhaust
Likely causes
- Worn spark plugs
- Weak ignition coils
- Vacuum leak
- Low fuel pressure
- Dirty or failing injectors
- Low compression
What to check before replacing parts
1
Scan for cylinder-specific misfire codes
2
Inspect plugs and coils
3
Check fuel trims for vacuum leaks
4
Verify fuel pressure
5
Perform compression/leak-down testing if ignition and fuel checks pass
Use the code with symptoms
A code points at the system, not always the failed part. Add your vehicle, mileage, symptoms, and whether the check engine light is steady or flashing so the AI diagnostic can narrow the next step.