P0300 · Generic
P0300 - Random/Multiple Cylinder Misfire Detected
The ECU has detected misfires occurring on more than one cylinder, or misfires it cannot attribute to a single cylinder, based on erratic crankshaft speed sensed by the crankshaft position sensor.
Sourced from our reviewed reference database — not AI-generated.
Drive recommendation
If the check engine light is flashing, stop driving as soon as it is safe to do so — an active misfire can dump unburned fuel into the catalytic converter and destroy it within minutes. A steady, non-flashing light is safer to drive on briefly to get it diagnosed.
Most likely causes
Worn or fouled spark plugs
Failing ignition coil(s)
Vacuum leak
Low fuel pressure
Clogged or leaking fuel injector(s)
Low cylinder compression
Faulty mass airflow sensor
Contaminated fuel
Reported symptoms
- Rough idle
- Engine shaking or vibration
- Loss of power
- Check engine light flashing during an active misfire
- Hesitation on acceleration
- Reduced fuel economy
Recommended diagnostic checks
- Pull codes and check for companion cylinder-specific misfire codes (P0301 to P0308)
- Inspect spark plugs and ignition coils
- Smoke-test the intake for vacuum leaks
- Check fuel trims — positive trims point to a lean condition
- Test fuel pressure against spec
- Run a compression or leak-down test if a mechanical cause is suspected
What not to replace yet
Replacing every spark plug and coil at once before confirming the misfire pattern — a single failing coil or a vacuum leak is often mistaken for a full ignition system failure.
Frequently asked questions
Is P0300 the same as a single-cylinder misfire code?
No — P0300 means the ECU could not pin the misfire to one cylinder, or it is happening across more than one. Codes P0301 through P0308 point to a specific cylinder instead.
Can I keep driving with a P0300 code?
It depends on whether the check engine light is flashing. A flashing light means an active misfire that can damage the catalytic converter quickly — stop driving as soon as it is safe. A steady light is safer to drive on briefly.
Technical details
- Code
- P0300
- Make
- Generic
This information is for diagnostic guidance only and is not a substitute for a qualified technician's in-person inspection. Always confirm a cause with the recommended tests before replacing parts.
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